Method and apparatus for transmitting downlink control information in wireless communication system

ABSTRACT

A communication method and system for converging a 5G communication system for supporting higher data rates beyond a 4G system with a technology for Internet of Things (IoT) is disclosed. A method of a terminal in a wireless communication system is provided. The method includes receiving downlink control information (DCI) including frequency domain resource allocation information on a physical downlink control channel (PDCCH) from a base station, identifying an allocated resource for transmitting or receiving data based on the frequency domain resource allocation information, and transmitting or receiving the data on the allocated resource. When the frequency domain resource allocation information is based on a first bandwidth part of a first bandwidth and the DCI is for a second bandwidth part corresponding to a second bandwidth, the allocated resource is identified by applying a scaling factor based on the first bandwidth and the second bandwidth.

CROSS-REFERENCE TO RELATED APPLICATION(S)

This application is a Continuation Application of U.S. patentapplication Ser. No. 16/363,637, filed on Mar. 25, 2019, in the U.S.Patent and Trademark Office, which is based on and claims priority under35 U.S.C. § 119 to Korean Patent Application Serial Nos.10-2018-0033718, 10-2018-0039915, 10-2018-0044791, and 10-2018-0054517,filed on Mar. 23, 2018, Apr. 5, 2018, Apr. 18, 2018, and May 11, 2018,respectively, in the Korean Intellectual Property Office, the entiredisclosure of each of which is incorporated herein by reference.

BACKGROUND 1. Field

The present disclosure relates generally to a method and an apparatusfor transmitting downlink control information in a wirelesscommunication system.

2. Description of Related Art

To meet the demand for wireless data traffic having increased sincedeployment of 4^(th) Generation (4G) communication systems, efforts havebeen made to develop an improved 5^(th) Generation (5G) or pre-5Gcommunication system. Therefore, the 5G or pre-5G communication systemmay also be referred to as a “beyond 4G network” or a “post long-termevolution (LTE) system”. The 5G communication system is to beimplemented in higher frequency (mmWave) bands (e.g., 60 GHz bands) inorder to accomplish higher data rates. To decrease the propagation lossof radio waves and increase the transmission distance, beamforming,massive multiple-input multiple-output (MIMO), full dimensional MIMO(FD-MIMO), array antenna, analog beamforming, and large-scale antennatechniques are being discussed for use in 5G communication systems.

In addition, in 5G communication systems, development for system networkimprovement is underway based on advanced small cells, cloud radioaccess networks (RANs), ultra-dense networks, device-to-device (D2D)communication, wireless backhaul, moving network, cooperativecommunication, coordinated multi-points (CoMP), reception-endinterference cancellation and the like. In the 5G system, hybridfrequency shift keying (FSK) and quadrature amplitude modulation (QAM)modulation (FQAM) and sliding window superposition coding (SWSC) asadvanced coding modulation (ACM), and filter bank multi carrier (FBMC),non-orthogonal multiple access (NOMA), and sparse code multiple access(SCMA) as advanced access technologies have been developed.

Additionally, the Internet is now evolving to the Internet of things(loT), wherein distributed entities, i.e., things, exchange and processinformation without human intervention. The Internet of everything(IoE), which is a combination of IoT technology and big data processingtechnology through connection with a cloud server, has also emerged.

As technology elements, such as “sensing technology”, “wired/wirelesscommunication and network infrastructure”, “service interfacetechnology”, and “security technology” have been demanded for IoTimplementation, a sensor network, machine-to-machine (M2M)communication, machine-type communication (MTC), and so forth haverecently been researched. Such an IoT environment may provideintelligent Internet technology services that create a new value tohuman life by collecting and analyzing data generated by connectedthings. The IoT may be applied to a variety of fields including smarthomes, smart buildings, smart cities, smart cars or connected cars,smart grids, health care, smart appliances and advanced medical servicesthrough convergence and combination between existing informationtechnology (IT) and various industrial applications.

In line with this, various attempts have been made to apply 5Gcommunication systems to IoT networks. For example, technologies such asa sensor network, MTC, and M2M communication may be implemented bybeamforming, MIMO, and array antennas. Application of a cloud RAN as theabove described big data processing technology may also be considered tobe as an example of convergence between the 5G technology and the IoTtechnology.

In a 5G system, the number of times of blind-decoding of a physicaldownlink control channel (PDCCH) by a terminal may be limited by thenumber of downlink control information (DCI) formats configured to bemonitored, the number of PDCCH candidates, and the total number ofcontrol channel elements (CCEs) constituting a search space. Sincemultiple search space sets are monitored at a particular time point,there may occur a case in which the above described limiting conditionfails to be satisfied, and a method for selecting (or dropping) only aparticular PDCCH candidate in a pre-configured search space is needed inthis situation.

In the 5G system, a size of a fallback DCI format may be determined bythe size of an initial bandwidth part. In this example, if the size of abandwidth part currently being activated is different from that of aninitial bandwidth part, scheduling may be limited.

SUMMARY

The present disclosure has been made to address at least thedisadvantages described above and to provide at least the advantagesdescribed below.

In accordance with an aspect of the present disclosure, a method of aterminal in a wireless communication system is provided. The method mayinclude receiving DCI including frequency domain resource allocationinformation on a physical downlink control channel (PDCCH) from a basestation, identifying an allocated resource for transmitting or receivingdata based on the frequency domain resource allocation information, andtransmitting or receiving the data on the allocated resource. When thefrequency domain resource allocation information is based on a firstbandwidth part of a first bandwidth and the DCI is for a secondbandwidth part corresponding to a second bandwidth, the allocatedresource is identified by applying a scaling factor based on the firstbandwidth and the second bandwidth.

In accordance with an aspect of the present disclosure, a method of abase station in a wireless communication system is provided. The methodmay include generating DCI including frequency domain resourceallocation information, the frequency domain resource allocationinformation indicating an allocated resource for transmitting orreceiving data, transmitting the DCI on a PDCCH from a base station andtransmitting or receiving the data on the allocated resource. When thefrequency domain resource allocation information is based on a firstbandwidth part of a first bandwidth and the DCI is for a secondbandwidth part corresponding to a second bandwidth, the allocatedresource is identified by applying a scaling factor based on the firstbandwidth and the second bandwidth.

In accordance with an aspect of the present disclosure, a terminal in awireless communication system is provided. The terminal may include atransceiver and a controller coupled with the transceiver. Thecontroller may be configured to receive DCI including frequency domainresource allocation information on a PDCCH from a base station, identifyan allocated resource for transmitting or receiving data based on thefrequency domain resource allocation information, and transmit orreceive the data on the allocated resource. When the frequency domainresource allocation information is based on a first bandwidth part of afirst bandwidth and the DCI is for a second bandwidth part correspondingto a second bandwidth, the allocated resource is identified by applyinga scaling factor based on the first bandwidth and the second bandwidth.

In accordance with an aspect of the present disclosure, a base stationin a wireless communication system is provided. The base station mayinclude a transceiver and a controller coupled with the transceiver. Thecontroller may be configured to generate DCI including frequency domainresource allocation information, the frequency domain resourceallocation information indicating an allocated resource for transmittingor receiving data, transmit the DCI on a physical downlink controlchannel (PDCCH) from a base station, and transmit or receive the data onthe allocated resource. When the frequency domain resource allocationinformation is based on a first bandwidth of a first bandwidth part andthe DCI is for a second bandwidth part corresponding to a secondbandwidth, the allocated resource is identified by applying a scalingfactor based on the first bandwidth and the second bandwidth.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other aspects, features and advantages of certainembodiments of the disclosure will be more apparent from the followingdetailed description taken in conjunction with the accompanyingdrawings, in which:

FIG. 1 is a diagram of a time-frequency domain in 5G, according to anembodiment;

FIG. 2 is a diagram of a structure of a frame, a subframe, and a slot in5G, according to an embodiment;

FIG. 3 is a diagram of an example of configuration of a bandwidth partin 5G, according to an embodiment;

FIG. 4 is a diagram of an example of configuration of a control resourceset of a downlink control channel in 5G, according to an embodiment;

FIG. 5 is a diagram of a structure of a downlink control channel in 5G,according to an embodiment;

FIG. 6 is a flowchart of a method of a base station and a terminal,according to a first embodiment;

FIG. 7 is a flowchart of a method of a base station and a terminal,according to embodiment 1-1;

FIG. 8 is a flowchart of a method of a base station and a terminal,according to embodiment 1-1-1;

FIG. 9 is a flowchart of a method of a base station and a terminal,according to embodiment 1-2;

FIG. 10 is a flowchart of a method of a base station and a terminal,according to embodiment 1-4-4;

FIG. 11 is flowchart of a terminal procedure, according to embodiment2-4;

FIG. 12 is flowchart of a terminal procedure, according to embodiment2-5;

FIG. 13 is flowchart of a terminal procedure, according to embodiment2-6;

FIG. 14 is a diagram of an internal configuration of a terminal,according to an embodiment; and

FIG. 15 is a diagram illustrating an internal configuration of a basestation, according to an embodiment.

DETAILED DESCRIPTION

Embodiments of the disclosure will be described herein below withreference to the accompanying drawings. However, the embodiments of thedisclosure are not limited to the specific embodiments and should beconstrued as including all modifications, changes, equivalent devicesand methods, and/or alternative embodiments of the present disclosure.In the description of the drawings, similar reference numerals are usedfor similar elements,

The terms “have,” “may have,” “include,” and “may include” as usedherein indicate the presence of corresponding features (for example,elements such as numerical values, functions, operations, or parts), anddo not preclude the presence of additional features.

The terms “A or B,” “at least one of A or/and B,” or “one or more of Aor/and B” as used herein include all possible combinations of itemsenumerated with them. For example, “A or B,” “at least one of A and B,”or “at least one of A or B” means (1) including at least one A, (2)including at least one B, or (3) including both at least one A and atleast one B.

The terms such as “first” and “second” as used herein may usecorresponding components regardless of importance or an order and areused to distinguish a component from another without limiting thecomponents. These terms may be used for the purpose of distinguishingone element from another element. For example, a first user device and asecond user device indicate different user devices regardless of theorder or importance. For example, a first element may be referred to asa second element without departing from the scope the disclosure, andsimilarly, a second element may be referred to as a first element.

When an element (for example, a first element) is “(operatively orcommunicatively) coupled with/to” or “connected to” another element (forexample, a second element), the element may be directly coupled with/toanother element, and there may be an intervening element (for example, athird element) between the element and another element. However, when anelement (for example, a first element) is “directly coupled with/to” or“directly connected to” another element (for example, a second element),there is no intervening element (for example, a third element) betweenthe element and another element.

The expression “configured to (or set to)” as used herein may be usedinterchangeably with “suitable for,” “having the capacity to,” “designedto,” “adapted to,” “made to,” or “capable of” according to a context.The term “configured to (set to)” does not necessarily mean“specifically designed to” in a hardware level. Instead, the expression“apparatus configured to . . . ” may mean that the apparatus is “capableof . . . ” along with other devices or parts in a certain context. Forexample, “a processor configured to (set to) perform A, B, and C” maymean a dedicated processor (e.g., an embedded processor) for performinga corresponding operation, or a generic-purpose processor (e.g., acentral processing unit (CPU) or an application processor (AP)) capableof performing a corresponding operation by executing one or moresoftware programs stored in a memory device.

The terms used in describing the various embodiments of the disclosureare for the purpose of describing particular embodiments and are notintended to limit the disclosure. As used herein, the singular forms areintended to include the plural forms as well, unless the context clearlyindicates otherwise. All of the terms used herein including technical orscientific terms have the same meanings as those generally understood byan ordinary skilled person in the related art unless they are definedotherwise. Terms defined in a generally used dictionary should beinterpreted as having the same or similar meanings as the contextualmeanings of the relevant technology and should not be interpreted ashaving ideal or exaggerated meanings unless they are clearly definedherein. According to circumstances, even the terms defined in thisdisclosure should not be interpreted as excluding the embodiments of thedisclosure.

The term “module” as used herein may, for example, mean a unit includingone of hardware, software, and firmware or a combination of two or moreof them. The “module” may be interchangeably used with, for example, theterm “unit”, “logic”, “logical block”, “component”, or “circuit”. The“module” may be a minimum unit of an integrated component element or apart thereof. The “module” may be a minimum unit for performing one ormore functions or a part thereof. The “module” may be mechanically orelectronically implemented. For example, the “module” according to thedisclosure may include at least one of an application-specificintegrated circuit (ASIC) chip, a field-programmable gate array (FPGA),and a programmable-logic device for performing operations which has beenknown or are to be developed hereinafter.

An electronic device according to the disclosure may include at leastone of, for example, a smart phone, a tablet personal computer (PC), amobile phone, a video phone, an electronic book reader (e-book reader),a desktop PC, a laptop PC, a netbook computer, a workstation, a server,a personal digital assistant (PDA), a portable multimedia player (PMP),a MPEG-1 audio layer-3 (MP3) player, a mobile medical device, a camera,and a wearable device. The wearable device may include at least one ofan accessory type (e.g., a watch, a ring, a bracelet, an anklet, anecklace, a glasses, a contact lens, or a head-mounted device (HMD)), afabric or clothing integrated type (e.g., an electronic clothing), abody-mounted type (e.g., a skin pad, or tattoo), and a bio-implantabletype (e.g., an implantable circuit).

The electronic device may be a home appliance. The home appliance mayinclude at least one of, for example, a television, a digital video disk(DVD) player, an audio, a refrigerator, an air conditioner, a vacuumcleaner, an oven, a microwave oven, a washing machine, an air cleaner, aset-top box, a home automation control panel, a security control panel,a TV box (e.g., Samsung HomeSync™, Apple TV™, or Google TV™), a gameconsole (e.g., Xbox™ and PlayStation™), an electronic dictionary, anelectronic key, a camcorder, and an electronic photo frame.

The electronic device may include at least one of various medicaldevices (e.g., various portable medical measuring devices (a bloodglucose monitoring device, a heart rate monitoring device, a bloodpressure measuring device, a body temperature measuring device, etc.), amagnetic resonance angiography (MRA), a magnetic resonance imaging(MRI), a computed tomography (CT) machine, and an ultrasonic machine), anavigation device, a global positioning system (GPS) receiver, an eventdata recorder (EDR), a flight data recorder (FDR), a vehicleinfotainment device, an electronic device for a ship (e.g., a navigationdevice for a ship, and a gyro-compass), avionics, security devices, anautomotive head unit, a robot for home or industry, an automatic tellermachine (ATM) in banks, point of sales (POS) devices in a shop, or anIoT device (e.g., a light bulb, various sensors, electric or gas meter,a sprinkler device, a fire alarm, a thermostat, a streetlamp, a toaster,a sporting goods, a hot water tank, a heater, a boiler, etc.).

The electronic device may include at least one of a part of furniture ora building/structure, an electronic board, an electronic signaturereceiving device, a projector, and various kinds of measuringinstruments (e.g., a water meter, an electric meter, a gas meter, and aradio wave meter). The electronic device may be a combination of one ormore of the aforementioned various devices. The electronic device mayalso be a flexible device. Further, the electronic device is not limitedto the aforementioned devices, and may include an electronic deviceaccording to the development of new technology.

Herein, the term “unit” may refer to software or hardware elements, suchas a field-programmable gate array (FPGA) and an ASIC, and the “unit”may perform any role. However, the meaning of “unit” is not limited tosoftware or hardware. A “unit” may be configured to reside in a storagemedium that may be addressed, and may also be configured to reproduceone or more processors. Accordingly, for example, a “unit” includeselements such as software elements, object-oriented software elements,class elements, and task elements; and processors, functions,attributes, procedures, subroutines, segments of program code, drivers,firmware, microcode, circuits, data, databases, data structures, tables,arrays, and variables. The functions provided in the elements and“units” may be combined with a smaller number of elements and “units” ormay be further separated into additional elements and “units”. Inaddition, the elements and the “units” may also be implemented toreproduce one or more CPUs within a device or a security multimediacard.

In the disclosure, the term “user” indicates a person using anelectronic device or a device (e.g., an artificial intelligenceelectronic device) using an electronic device.

An embodiment implemented based on a 5G system is described below by wayof example, but embodiments may be applied to other communicationsystems having a similar technical background or channel form. Forexample, LTE or LTE-A mobile communication and mobile communicationtechnology, developed after 5G, may be included in other communicationsystems. Therefore, according to the determination of those skilled inthe art, embodiments may be applied to other communication systemsthrough partial modification without departing from the scope of thedisclosure.

Further, in the following description of the disclosure, a detaileddescription of known functions or configurations incorporated hereinwill be omitted when the same may make the subject matter of thedisclosure rather unclear. The terms which will be described below aredefined in consideration of the functions in the disclosure, and may bedifferent according to the intention or practice of users and operators.Therefore, the definitions of the terms should be made based on thecontents throughout the specification.

A wireless communication system has been developed from a wirelesscommunication system providing a voice-centered service in the earlystage toward broadband wireless communication systems providinghigh-speed, high-quality packet data services compliant withcommunication standards, for example, high-speed packet access (HSPA),LTE or evolved universal terrestrial radio access (E-UTRA), LTE-advanced(LTE-A), and LTE-Pro of the 3rd Generation Partnership Project (3GPP),high-rate packet data (HRPD) and ultra-mobile broadband (UMB) of 3GPP2,802.16e of Institute of Electrical and Electronics Engineers (IEEE),etc.

As a representative example of broadband wireless communication systems,an LTE system adopts an orthogonal frequency division multiplexing(OFDM) scheme in a downlink (DL), and adopts a single carrier frequencydivision multiple access (SC-FDMA) scheme in an uplink (UL). The“uplink” refers to a radio link through which a terminal (a userequipment (UE) or a mobile station (MS)) transmits data or a controlsignal to a base station (BS) (or an eNodeB), and the “downlink” refersto a radio link through which a base station transmits data or a controlsignal to a terminal. The above described multiple access schemenormally allocates and operates time-frequency resources, which carrydata or control information to be transmitted according to users, so asto prevent the time-frequency resources from overlapping each other(e.g., establish orthogonality), thus making it possible to distinguishthe data or control information of one user from another.

As a future communication system since the LTE (e.g., a 5G communicationsystem) should be able to freely reflect various requirements such as auser and a service provider, and thus a service, which satisfies variousrequirements together, needs to be supported. The services consideredfor the 5G communication system include enhanced mobile broadband(eMBB), massive machine-type communication (mMTC), ultra-reliabilitylow-latency communication (URLLC), etc.

The eMBB aims to provide a higher data transfer rate than a datatransfer rate supported by the existing LTE, LTE-A, or LTE-Pro. Forexample, in the 5G communication system, the eMBB should be able toprovide a peak data rate of 20 Gbps in the downlink and a peak data rateof 10 Gbps in the uplink from the perspective of one base station. Also,the 5G communication system has to provide an increased user perceiveddata rate of a terminal simultaneously with providing the peak datarate. In order to satisfy these requirements, an improvement in varioustransmitting and receiving technologies, including a further improvedmulti-input multi-output (MIMO) transmission technology is required. Inthe current LTE, signals are transmitted using the transmissionbandwidth of up to 20 MHz in the used 2 GHz band, whereas the 5Gcommunication system uses a bandwidth wider than 20 MHz in the frequencyband of 3 to 6 GHz or more than 6 GHz, and thus can satisfy the datatransmission rate required in the 5G communication system.

In addition, the mMTC is being considered to support applicationservices such as IoT in the 5G communication system. The mMTC isrequired for access support for a large-scale terminal in a cell,coverage enhancement in a terminal, improved battery time, and costreduction of a terminal in order to efficiently provide the Internet ofthings. Since the IoT is attached to various sensors and various devicesso as to provide a communication function, the IoT should be able tosupport a large number of terminals (e.g., 1,000,000 terminals/km2) in acell. Also, the terminals supporting the mMTC are more likely to belocated in shaded areas that a cell fails to cover, such as anunderground of building due to the nature of services, and thus requiresa wider coverage than other services provided by the 5G communicationsystem. The terminals supporting the mMTC should be configured asinexpensive terminals and require very long battery life time, e.g., 10to 15 years, because it is difficult to frequently replace the batteryof the terminal.

The URLLC is a cellular-based wireless communication service used formission-critical purposes. For example, services used for a remotecontrol for a robot or machinery, industrial automation, unmanagedaerial vehicle, remote health care, emergency alert, etc., may beconsidered. Therefore, the communication provided by the URLLC shouldprovide very low latency and very high reliability. For example, aservice which supports URLLC should meet air interface latency of lessthan 0.5 milliseconds, and at the same time, have requirements of apacket error rate less than 10⁻⁵. Therefore, for the service thatsupports the URLLC, the 5G system should provide a transmit timeinterval (TTI) smaller than other services, and at the same time, designmatters for allocating a wide resource in a frequency band in order toensure the reliability of a communication link are required.

The three services considered for the 5G communication system (e.g., theeMBB, the URLLC, and the mMTC) may be multiplexed and transmitted in onesystem. In this configuration, in order to meet different requirementsthat the respective services have, it is possible to use differenttransmission/reception techniques and different transmission/receptionparameters between the services.

FIG. 1 is a diagram of a basic structure of a time-frequency domain(e.g., a radio resource domain) in which data or a control channel istransmitted in a 5G system, according to an embodiment.

Referring to FIG. 1, the horizontal axis represents the time domain andthe vertical axis represents the frequency domain. A basic unit ofresources in the time and frequency domain is a resource element (RE)101, and may be defined by one OFDM symbol 102 on the time axis and onesubcarrier 103 on the frequency axis. In the frequency domain, N_(SC)^(RB) (e.g., 12) consecutive REs may constitute one resource block (RB)104. In the time domain, N_(symb) ^(subframe) consecutive symbol REs mayconstitute one subframe 110.

FIG. 2 is a diagram of a structure of a frame, a subframe, and a slot in5G, according to an embodiment.

FIG. 2 illustrates an example of a structure of a frame 200, a subframe201, and a slot 202. One frame 200 may be defined as 10 ms. One subframe201 may be defined as 1 ms, and thus one frame 200 may include a totalof 10 subframes 201. One slot 202 or 203 may include 14 OFDM symbols(i.e., N_(symb) ^(slot), which represents the number of symbols perslot, =14). One subframe 201 may include one or more slots 202 or 203,and the number of slots 202 or 203 per subframe 201 may be changedaccording to μ 204 or 205 representing a set value of a subcarrierspacing. FIG. 2 illustrates a case in which μ=0 for a set value of asubcarrier spacing (as indicated by reference numeral 204) and a case inwhich μ=1 for a set value of a subcarrier spacing (as indicated byreference numeral 205). If μ=0 (as indicated by reference numeral 204),one subframe 201 may include one slot 202. If μ=1 (as indicated byreference numeral 205), one subframe 201 may include two slots 203. Thatis, N_(slot) ^(subframe,μ), which represents the number of slots persubframe, may be changed according to a set value μ of a subcarrierspacing, and thus N_(slot) ^(frame,μ), which represents the number ofslots per frame, may be changed. N_(slot) ^(subframe,μ) and N_(slot)^(frame,μ) according to a set value μ of a subcarrier spacing may bedefined as shown in Table 1 below.

TABLE 1 μ N_(symb) ^(slot) N_(slot) ^(frame,μ) N_(slot) ^(subframe,μ) 014 10 1 1 14 70 2 2 14 40 4 3 14 80 8 4 14 160 16 5 14 320 32

In the 5G system, scheduling information for uplink data (or a physicaluplink shared channel (PUSCH)) or downlink data (or a physical downlinkshared channel (PDSCH)) is delivered from a base station to a terminalthrough DCI. The terminal may monitor a fallback DCI format and anon-fallback DCI format for a PUSCH or a PDSCH. A fallback DCI formatmay include a fixed field predefined between the base station and theterminal, and a non-fallback DCI format may include a configurablefield.

The DCI may pass through a channel coding and modulation process and maythen be transmitted through a physical downlink control channel (PDCCH).A cyclic redundancy check (CRC) is attached to a payload of a DCImessage, and the CRC is scrambled by a radio network temporaryidentifier (RNTI) corresponding to identity of the terminal. DifferentRNTIs are used depending on the purpose of the DCI message (e.g.,UE-specific data transmission, power control command, or random accessresponse). The RNTI is not explicitly transmitted but is transmitted bybeing included in a CRC calculation process.

Upon receiving the DCI message transmitted on the PDCCH, the terminalchecks the CRC by using the allocated RNTI. If the check result of theCRC is correct, it can be seen that the corresponding message istransmitted to the terminal.

DCI for scheduling a PDSCH for system information (SI) may be scrambledwith a system information RNTI (SI-RNTI). DCI for scheduling a PDSCH fora random access response (RAR) message may be scrambled with a randomaccess RNTI (RA-RNTI). DCI for scheduling a PDSCH for a paging messagemay be scrambled with a paging RNTI (P-RNTI). DCI which providesnotification of a slot format indicator (SFI) may be scrambled with aslot format indicator RNTI (SFI-RNTI). DCI which provides notificationof transmit power control (TPC) may be scrambled with a transmit powercontrol RNTI (TPC-RNTI). DCI for scheduling a UE-specific PDSCH or PUSCHmay be scrambled with a cell RNTI (C-RNTI).

A DCI format 0_0 may be used as fallback DCI for scheduling a PUSCH, anda CRC may be scrambled by a C-RNTI in this example. The DCI format 0_0,the CRC of which is scrambled by the C-RNTI, may include the followingpieces of information as shown in Table 2.

TABLE 2 Identifier for DCI formats-[1] bit Frequency domain resourceassignment- [┌log₂(N_(RB) ^(UL,BWP) (N_(RB) ^(UL,BWP) + 1)/2)┐] bitsTime domain resource assignment-X bits Frequency hopping flag-1 bit.Modulation and coding scheme-5 bits New data indicator-1 bit Redundancyversion-2 bits HARQ process number-4 bits TPC command for scheduledPUSCH-[2] bits UL/supplementary UL (SUL) indicator-0 or 1 bit

A DCI format 0_1 may be used as non-fallback DCI for scheduling a PUSCH,and a CRC may be scrambled by a C-RNTI in this example. The DCI format0_1, the CRC of which is scrambled by the C-RNTI, may include thefollowing pieces of information as shown in Table 3.

TABLE 3 Carrier indicator-0 or 3 bits Ul/SUL indicator-0 or 1 bitIdentifier for DCI formats-[1] bits Bandwidth part indicator 0, 1, or 2bits Frequency domain resource assignment  For resource allocation type0, ┌NRB^(UL,BWP)/P┐ bits  For resource allocation type 1,┌LOG₂(NRB^(UL,BWP)(NRB^(UL,BWP) + 1)/2)┐ bits Time domain resourceassignment-1, 2, 3, or 4 bits Virtual resource block (VRB)-to-physicalresource block (PRB) mapping- 0 or 1 bit, only for resource allocationtype 1.  0 bit if only resource allocation type 0 is configured;  1 bitotherwise. Frequency hopping flag-0 or 1 bit, only for resourceallocation type 1.  0 bit if only resource allocation type 0 isconfigured;  1 bit otherwise. Modulation and coding scheme-5 bits Newdata indicator-1 bit Redundancy version-2 bits HARQ process number-4bits 1st downlink assignment index-1 or 2 bits  1 bit for semi-staticHARQ-ACK codebook;  2 bits for dynamic HARQ-ACK codebook with singleHARQ-ACK codebook. 2nd downlink assignment index-0 or 2 bits  2 bits fordynamic HARQ-ACK codebook with two HARQ-ACK sub-codebooks;  0 bitotherwise. TPC command for scheduled PUSCH-2 bits${SRS}\mspace{14mu}{resource}\mspace{14mu}{indicator}\text{-}\left\lceil {\log_{2}\left( {\sum\limits_{k = 1}^{L_{\max}}\;\left( \underset{k}{N_{SRS}} \right)} \right)} \right\rceil\mspace{14mu}{or}\mspace{14mu}\left\lceil {\log_{2}\left( N_{SRS} \right)} \right\rceil\mspace{14mu}{bits}$ ${\left\lceil {\log_{2}\left( {\sum\limits_{k = 1}^{L_{\max}}\;\left( \underset{k}{N_{SRS}} \right)} \right)} \right\rceil\mspace{14mu}{bits}\mspace{14mu}{for}\mspace{14mu}{non}\text{-}{codebook}\text{-}{based}\mspace{14mu}{PUSCH}\mspace{14mu}{transmission}}\;;$ ┌log₂(NSRS)┐ bits for codebook-based PUSCH transmission. Precodinginformation and number of layers-up to 6 bits Antenna ports-up to 5 bitsSRS request-2 bits CSI request-0, 1, 2, 3, 4, 5, or 6 bits Code blockgroup (CBG) transmission information-0, 2, 4, 6, or 8 bits PTRS-DMRSassociation-0 or 2 bits. beta_offset indicator-0 or 2 bits DMRS sequenceinitialization-0 or 1 bit

A DCI format 1_0 may be used as fallback DCI for scheduling a PDSCH, anda CRC may be scrambled by a C-RNTI in this example. The DCI format 1_0,the CRC of which is scrambled by the C-RNTI, may include the followingpieces of information as shown in Table 4.

TABLE 4 Identifier for DCI formats-[1] bit Frequency domain resourceassignment- [┌log₂(N_(RB) ^(UL,BWP) (N_(RB) ^(UL,BWP) + 1)/2)┐] bitsTime domain resource assignment-X bits VRB-to-PRB mapping-1 bit.Modulation and coding scheme-5 bits New data indicator-1 bit Redundancyversion-2 bits HARQ process number-4 bits Downlink assignment index-2bits TPC command for scheduled PUCCH-[2] bits Physical uplink controlchannel (PUCCH) resource indicator-3 bits PDSCH-to-HARQ feedback timingindicator-[3] bits

A DCI format 1_1 may be used as non-fallback DCI for scheduling a PDSCH,and a CRC may be scrambled by a C-RNTI in this example. The DCI format1_1, the CRC of which is scrambled by the C-RNTI, may include thefollowing pieces of information as shown in Table 5.

TABLE 5 Carrier indicator-0 or 3 bits Identifier for DCI formats-[1]bits Bandwidth part indicator-0, 1, or 2 bits Frequency domain resourceassignment For resource allocation type 0, ┌N_(RB) ^(DL,BWP)/P┐ bits Forresource allocation type 1, ┌log₂(N_(RB) ^(DL,BWP)(N_(RB) ^(DL,BWP) +1)/2)┐ bits Time domain resource assignment-1, 2, 3, or 4 bitsVRB-to-PRB mapping-0 or 1 bit, only for resource allocation type 1. 0bit if only resource allocation type 0 is configured; 1 bit otherwise.PRB bundling size indicator-0 or 1 bit Rate matching indicator-0, 1, or2 bits Zero power (ZP) CSI-RS trigger-0, 1, or 2 bits For transportblock 1: Modulation and coding scheme-5 bits New data indicator-1 bitRedundancy version-2 bits For transport block 2: Modulation and codingscheme-5 bits New data indicator-1 bit Redundancy version-2 bits HAW)process number-4 bits Downlink assignment index-0, 2, or 4 bits TPCcommand for scheduled PUCCH-2 bits PUCCH resource indicator-3 bitsPDSCH-to-HARQ_feedback timing indicator-3 bits Antenna ports-4, 5, or 6bits Transmission configuration indication-0 or 3 bits SRS request-2bits CBG transmission information-0, 2, 4, 6, or 8 bits CBG flushing outinformation-0 or 1 bit DMRS sequence initialization-1 bit

FIG. 3 is a diagram of an example of configuration of a bandwidth partin 5G, according to an embodiment. More specifically, FIG. 3 illustratesan example in which a terminal bandwidth 300 includes two bandwidthparts (e.g., a bandwidth part #1 301 and a bandwidth part #2 302). Abase station may configure one or more bandwidth parts for a terminal,and may configure the following pieces of information (e.g., at leastone of a bandwidth part identifier, a bandwidth part location, asubcarrier spacing, and a cyclic prefix) for each bandwidth part asshown in Table 6.

TABLE 6 BWP ::= SEQUENCE {   bwp-Id   BWP-Id,  (bandwidth partidentifier)     locationAndBandwidth  INTEGER (1..65536),   (bandwidthpart location)     subcarrierSpacing  ENUMERATED {n0, n1, n2, n3, n4,n5},     (subcarrier spacing)     cyclicPrefix  ENUMERATED { extended }  (cyclic prefix)

In addition to the above described pieces of configuration information,various parameters related to a bandwidth part may be configured for theterminal. The base station may deliver the above described pieces ofinformation to the terminal through higher layer signaling, such asradio resource control (RRC) signaling. At least one bandwidth partamong the one or more configured bandwidth parts may be activated.Whether the configured bandwidth part is activated may besemi-statically delivered from the base station to the terminal throughRRC signaling, or may be dynamically delivered from the base station tothe terminal through a medium access control (MAC) control element (CE)or DCI.

The configuration of a bandwidth part supported by the 5G system may beused for various purposes.

If a bandwidth supported by the terminal is smaller than a systembandwidth, the above described configuration of a bandwidth part mayprovide support. A frequency location (configuration information 2) of abandwidth part is configured for the terminal as shown in Table 4, andthus the terminal can transmit or receive data at a particular frequencylocation in the system bandwidth.

In order to support different numerologies, the base station mayconfigure multiple bandwidth parts for the terminal. In order to provideany terminal with support for transmissions/receptions of data usingboth a subcarrier spacing of 15 kHz and a subcarrier spacing of 30 kHz,two bandwidth parts may be configured with the subcarrier spacing of 15kHz and the subcarrier spacing of 30 kHz, respectively. The differentbandwidth parts may be frequency-division-multiplexed, and if data is tobe transmitted or received with a particular subcarrier spacing, abandwidth part configured with the relevant subcarrier spacing may beactivated.

In order to reduce power consumed by the terminal, the base station mayconfigure bandwidth parts having different bandwidths for the terminal.If the terminal supports very large bandwidth, such as a bandwidth of100 MHz, and always transmits or receives data in the relevantbandwidth, very large power consumption may be caused. Particularly, ina situation where there is no traffic, execution of unnecessarymonitoring of a downlink control channel in a large bandwidth such as100 MHz is very inefficient from the perspective of power consumption.In order to reduce power consumed by the terminal, the base station mayconfigure a bandwidth part having a relatively small bandwidth, such asa bandwidth of 20 MHz, for the terminal.

When there is no traffic, the terminal may perform a monitoringoperation in the bandwidth part having the bandwidth of 20 MHz, and ifdata is generated, may transmit or receive data in the bandwidth parthaving the bandwidth of 100 MHz according to an instruction of the basestation.

In the above described method for configuring a bandwidth part,terminals before being RRC-connected may receive configurationinformation on an initial bandwidth part through a master informationblock (MIB) at an initial access stage. More specifically, the terminalmay receive, from a MIB of a physical broadcast channel (PBCH),configuration of a control resource set (CORESET) for a downlink controlchannel through which DCI for scheduling a system information block(SIB) can be transmitted. A bandwidth of the CORESET configured throughthe MIB may be regarded as an initial bandwidth part, and the terminalmay receive a PDSCH, through which an SIB is transmitted, in theconfigured initial bandwidth part. The initial bandwidth part may beused to receive an SIB, and may also be utilized for other systeminformation (OSI), paging, and random access.

FIG. 4 is a diagram of a control resource set (CORESET) for transmissionof a downlink control channel in a 5G wireless communication system,according to an embodiment. More specifically, FIG. 4 illustrates anexample in which a terminal bandwidth part 410 is configured on thefrequency axis and two CORESETs (a CORESET #1 401 and a CORESET #2 402)are configured in one slot 420 on the time axis. The CORESETs 401 and402 may be configured in a particular frequency resource 403 in theentire terminal bandwidth part 410 on the frequency axis. The CORESETs401 and 402 may be configured as one or more OFDM symbols on the timeaxis, which may be defined as a CORESET duration 404. In FIG. 4, theCORESET #1 401 is configured as a CORESET duration of two symbols, andthe CORESET #2 402 is configured as a CORESET duration of one symbol.

The above described CORESET in the 5G system may be configured for theterminal through higher layer signaling (e.g., system information, aMIB, or RRC signaling) by the base station. The configuration of aCORESET for the terminal signifies provision of at least one of aCORESET identity, a frequency location of a CORESET, and a symbolduration of a CORESET. Examples of CORESET configuration information mayinclude the following pieces of information as shown in Table 7 (atleast one piece of information among CORESET identity, frequency-axisresource allocation information, time-axis resource allocationinformation, mapping type, resource element group (REG) bundle size,interleaver size, interleaver shift, and QCL configuration information).

TABLE 7 ControlResourceSet ::= SEQUENCE {   -- Corresponds to L1parameter ‘CORESET-ID’   controlResourceSetId ControlResourceSetId, (control resource set identity)   frequencyDomainResources BIT STRING(SIZE (45)),  (frequency-axis resource allocation information)  duration   INTEGER (1..maxCoReSetDuration),  (time-axis resourceallocation information   cce-REG-MappingType   CHOICE {  (CCE-to-REGmapping type)    interleaved.   SEQUENCE {      reg-BundleSize  ENUMERATED {n2, n3, n6},   (REG bundle size)      precoderGranularity  ENUMERATED {sameAsREG-bundle, allContiguousRBs},      interleaverSize  ENUMERATED {n2, n3, n6}      (interleaver size)      shiftIndex  INTEGER(0-maxNrofPhysicalResourceBlocks-1)       OPTIONAL    (interleaver shift)   },   noninterleaved  NULL   },  tci-StatesPDCCH   SEQUENCE(SIZE (1..maxNrofTCI-StatesPDCCH)) OFTCI-StateId      OPTIONAL,  (QCL configuration information)  tci-PresentInDCI  ENUMERATED {enabled} }

FIG. 5 is a diagram of a basic unit of time and frequency resourcesconstituting a downlink control channel usable in a 5G system, accordingto an embodiment.

Referring to FIG. 5, a basic unit of time and frequency resourcesconstituting a control channel is named “REG” 503, wherein the REG 503may be defined as one OFDM symbol 501 on the time axis and may bedefined as 1 PRB 502 (e.g., 12 subcarriers) on the frequency axis. Adownlink control channel allocation unit may be configured byconcatenating the REGs 503.

If a basic unit, in which a downlink control channel is allocated, is acontrol channel element (CCE) 504 in the 5G system, one CCE 504 mayinclude multiple REGs 503. In the REG 503, the REG 503 may include 12REs, and if one CCE 504 includes six REGs 503, the one CCE 504 mayinclude 72 REs. If a downlink CORESET is configured, the relevantdownlink CORESET may include multiple CCEs 504, and a particulardownlink control channel may be mapped to one or more CCEs 504 accordingto aggregation levels (ALs) in the CORESET, and the downlink controlchannel mapped to the one or more CCEs 504 may be transmitted. The CCEs504 in the CORESET are distinguished by numbers, and the numbers may beassigned according to a logical mapping scheme.

A basic unit (e.g., the REG 503), of a downlink control channelillustrated in FIG. may include REs, to which DCI is mapped, and allregions in which demodulation reference signals (DMRSs) 505, which arereference signals for decoding of the REGs, are mapped. As illustratedin FIG. 5, the three DMRSs 505 may be transmitted in the one REG 503.

The numbers of CCEs used to transmit a PDCCH may be 1, 2, 4, 8, and 16according to the ALs, and the different numbers of CCEs may be used toimplement link adaptation of a downlink control channel. If AL=L, onedownlink control channel may be transmitted through L CCEs. A terminalshould detect a signal in a state in which the terminal does not knowinformation on a downlink control channel, and a search spacerepresenting a set of CCEs is defined for blind-decoding. Since a searchspace is a set of control channel candidates including CCEs that theterminal should attempt to decode at a given AL and there are multipleALs which make respective groups from 1, 2, 4, 8, and 16 CCEs intorespective groups, the terminal has multiple search spaces. A searchspace set may be defined as a set of search spaces at all configuredALs.

Search spaces may be classified into a common search space and aUE-specific search space. A specific group of terminals or all terminalsmay search (blind-decode) a common search space of a PDCCH in order toreceive dynamic scheduling for system information or cell-common controlinformation such as a paging message. PDSCH scheduling allocationinformation for transmission of an SIB including operator informationand the like of a cell blind-decode may be received throughblind-decoding of a common search space of a PDCCH. Since a specificgroup of terminals or all terminals should receive a PDCCH, a commonsearch space may be defined as a set of pre-agreed CCEs. Schedulingallocation information on a UE-specific PDSCH or PUSCH may be receivedthrough blind-decoding a UE-specific search space of a PDCCH. AUE-specific search space is a function of an identity of a terminal andvarious system parameters, and may be defined to be UE-specific.

In the 5G system, a parameter of a search space for a PDCCH may beconfigured for the terminal by the base station through higher layersignaling (e.g., SIB, MIB, or RRC signaling). The base station mayconfigure, for the terminal, at least one piece of information among thenumber of PDCCH candidates at each aggregation level L, a cycle formonitoring of a search space, occasion of monitoring of a search spacein the unit of symbol in a slot, search space type (common search spaceor UE-specific search space), a combination of an RNTI and a DCI formatto be monitored in a relevant search space, and an index of a CORESET inwhich a search space is to be monitored. Examples of the informationconfigured for the terminal by the base station may include thefollowing pieces of information in Table 8 (at least one piece ofinformation among search space identity, CORESET identity, monitoringslot level periodicity, monitoring symbol in a slot, the number of PDCCHcandidates for each AL, and search space type).

TABLE 8 SearchSpace ::=  SEQUENCE {   -- Identity of the search space.SearchSpaceId = 0 identifies the SearchSpace configured via PBCH (MIB)or ServingCellConfigCommon.   searchSpaceId   SearchSpaceId,  (searchspace identity)   controlResourceSetId  ControlResourceSetId,  (controlresource set identity)   monitoringSlotPeriodicityAndOffset CHOICE { (monitoring slot level periodicity)    sl1   NULL,    sl2   INTEGER(0..1),    sl4   INTEGER (0..3),    sl5   INTEGER (0..4),    sl8  INTEGER (0..7),    sl10   INTEGER (0..9),    sl16   INTEGER (0..15),   sl20   INTEGER (0..19)   }  OPTIONAL,   monitoringSymbolsWithinSlot  BIT STRING (SIZE (14))    OPTIONAL,  (monitoring symbol in slot)  nrofCandidates   SEQUENCE {  (number of PDCCH candidates for eachaggregation level)    aggregationLevel1   ENUMERATED {n0, n1, n2, n3,n4, n5, n6, n8},    aggregationLevel2   ENUMERATED {n0, n1, n2, n3, n4,n5, n6, n8},    aggregationLevel4   ENUMERATED {n0, n1, n2, n3, n4, n5,n6, n8},    aggregationLevel8   ENUMERATED {n0, n1, n2, n3, n4, n5, n6,n8},    aggregationLevel16   ENUMERATED {n0, n1, n2, n3, n4, n5, n6,n8},   },   scarchSpaceType    CHOICE {   (search space type)    --Configures this search space as common search space (CSS) and DCIformats to monitor.    common   SEQUENCE {   (common search space)   }   ue-Specific   SEQUENCE {   (UE-specific search space      --Indicateswhether the UE monitors in this USS for DCI formats 0-0 and 1-0 or forformats 0-1 and 1-1.     formats   ENUMERATED {formats0-0-And-1-0,formats0-1-And-1-1},     ...    }

The base station may configure one or more search space sets for theterminal according to the configuration information. The base stationmay configure a search space set 1 and a search space set 2 for theterminal, may configure the terminal so as to monitor a DCI format A,scrambled with an X-RNTI in the search space set 1, in a common searchspace, and may configure the terminal so as to monitor a DCI format B,scrambled with a Y-RNTI in the search space set 2, in a UE-specificsearch space.

According to the above described configuration information, one or moresearch space sets may exist in a common search space or a UE-specificsearch space. Search space set #1 and search space set #2 may beconfigured as a common search space, and search space set #3 and searchspace set #4 may be configured as a UE-specific search space.

The following combination of a DCI format and an RNTI may be monitoredin a common search space.

-   -   DCI format 0_0/1_0 with CRC scrambled by cell-RNTI (C-RNTI),        configured scheduling RNTI (CS-RNTI), semi-persistent        (SP)-CSI-RNTI, random access RNTI (RA-RNTI), temporary cell RNTI        (TC-RNTI), paging RNTI (P-RNTI), system information RNTI        (SI-RNTI);    -   DCI format 2_0 with CRC scrambled by a slot format indicator        (SFI)-RNTI    -   DCI format 2_1 with CRC scrambled by interruption RNTI        (INT-RNTI);    -   DCI format 2_2 with CRC scrambled by transmit power control for        PUSCH RNTI (TPC-PUSCH-RNTI), transmit power control for PUCCH        RNTI (TPC-PUCCH-RNTI);    -   DCI format 2_3 with CRC scrambled by transmit power control for        SRS RNTI (TPC-SRS-RNTI);

The following combination of a DCI format and an RNTI may be monitoredin a UE-specific search space.

-   -   DCI format 0_0/1_0 with CRC scrambled by C-RNTI, CS-RNTI,        TC-RNTI;    -   DCI format 1_0/1_1 with CRC scrambled by C-RNTI, CS-RNTI,        TC-RNTI.

The above specified RNTIs may comply with the following definition anduses.

C-RNTI: use for scheduling UE-specific PDSCH;

TC-RNTI: use for scheduling UE-specific PDSCH;

CS-RNTI: use for semi-statically configured UE-specific PDSCHscheduling;

RA-RNTI: use for scheduling PDSCH at random access stage;

P-RNTI: use for scheduling of PDSCH for transmitting paging

SI-RNTI: use for scheduling of PDSCH for transmitting systeminformation;

INT-RNTI: use for providing notification of whether PDSCH is punctured;

TPC-PUSCH-RNTI: use for indicating power control command for PUSCH;

TPC-PUCCH-RNTI: use for indicating power control command for PUCCH;

TPC-SRS-RNTI: use for indicating power control command for SRS.

The above specified DCI formats may comply with the followingdefinitions in Table 9.

TABLE 9 DCI format Use 0_0 Scheduling of PUSCH in one cell 0_1Scheduling of PUSCH in one cell 1_0 Scheduling of PDSCH in one cell 1_1Scheduling of PDSCH in one cell 2_0 Notifying a group of UEs of the slotformat 2_1 Notifying a group of UEs of the PRB(s) and OFDM symbol(s)where UE may assume no transmission is intended for the UE 2_2Transmission of TPC commands for PUCCH and PUSCH 2_3 Transmission of agroup of TPC commands for SRS transmissions by one or more UEs

In the 5G system, a search space at an aggregation level L in a CORESETp and a search space set s may be expressed by Equation (1) below.

$\begin{matrix}{{L \cdot \left\{ {\left( {Y_{p,n_{s,f}^{\mu}} + \left\lfloor \frac{m_{s,n_{CI}} \cdot N_{{CCE},p}}{L \cdot M_{p,s,\max}^{(L)}} \right\rfloor + n_{CI}} \right){mod}\left\lfloor {N_{{CCE},p}/L} \right\rfloor} \right\}} + i} & (1)\end{matrix}$

In Equation (1) L represents aggregation level, n_(CI) representscarrier index, N_(CCE,p) represents the total number of CCEs existing ina CORESET p, n_(s,f) ^(μ) represents slot index, M_(p,s,max) ^((L))represents the number of PDCCH candidates at an aggregation level L,m_(s,n) _(CI) =0, . . . , M_(p,s,max) ^((L))−1 represents an index of aPDCCH candidate at an aggregation level L, i=0, . . . , L−1; Y_(p,n)_(s,f) _(μ) =(A_(p)·Y_(p,n) _(s,f) _(μ) ⁻¹)mod D, Y_(p,−1)=n_(RNTI)≠0,A₀=39827, A₁=39829, A₂=39839, and D=65537, and n_(RNTI) representsterminal identify.

A value of Y_(p,n_(s,f) ^(μ)) may correspond to 0 in the case of acommon search space.

A value of Y_(p,n_(s,f) ^(μ)) may correspond to a value changedaccording to an identity of a terminal (a C-RNTI or an ID configured forthe terminal by a base station) and a time index, in the case of aUE-specific search space.

First Embodiment

In the 5G system, multiple search space sets may be configured to havedifferent parameters (e.g., the parameters in Table 8). Accordingly,groups of search space sets monitored by the terminal may becomedifferent according to time points. If search space set #1 is configuredat intervals of an X-slot cycle, search space set #2 is configured atintervals of a Y-slot cycle, and X is different from Y, a terminal maymonitor both search space set #1 and search space set #2 in a particularslot, and may monitor either search space set #1 or search space set #2in a particular slot.

In the 5G system, a method for determining the maximum number of timesof blind-decoding of a PDCCH by a terminal may consider the followingconditions.

[Condition 1]

The number of DCI formats having different sizes monitored per slot doesnot exceed X. X may be, for example, 4 or 5.

[Condition 2]

The number of DCI formats, which have different sizes and each of whicha CRC is scrambled by a C-RNTI, among pieces of DCI monitored per slotdoes not exceed Y. Y may be, for example, 3 or 4.

[Condition 3]

The number of PDCCH candidates which can be monitored per slot does notexceed Z. Values of Z may be different according to subcarrier spacings,and may be defined as shown in Table 10 below.

TABLE 10 Maximum number of PDCCH candidates per slot and μ per servingcell (Z) 0 44 1 36 2 22 3 20

In Table 10, a subcarrier spacing may be defined as 15·2^(μ) kHz.

[Condition 4]

The number of CCEs constituting all search spaces per slot (in thisexample, all search spaces signifies all CCE sets corresponding to aunion region of multiple search space sets) does not exceed W. Values ofW may be different according to subcarrier spacings, and may be definedas shown in Table 11 below.

TABLE 11 Maximum number of CCEs per slot and per serving μ cell (W) 0 561 56 2 48 3 32

In Table 11, a subcarrier spacing may be defined as 15·2^(μ) kHz.

For convenience of description, a situation in which conditions 1, 2, 3,and 4 are all satisfied at a particular time point is defined as“condition A”. Accordingly, non-satisfaction of condition A may implythat at least one condition among conditions 1, 2, 3, and 4 is notsatisfied. Condition A may be defined as a search space configurationcondition or as a search space configuration-related condition.

The base station may adjust search space parameters (e.g., theparameters in Table 8) such that the above described condition A issatisfied at all time points so as to configure a search space for theterminal.

Alternatively, according to configuration of a search space by the basestation, there may occur a case in which the above described condition Ais not satisfied at a particular time point. If the above describedcondition A is not satisfied at a particular time point, only some ofsearch spaces may be selected or dropped so that condition A can besatisfied at the relevant time point.

FIG. 6 is a flowchart of a method of a base station and a terminal,according to the embodiment.

Referring to FIG. 6, at step 601, the base station determines whetherthe above described condition A is satisfied in a particular slot inwhich a PDCCH is to be transmitted. At step 601, the terminal determineswhether the above described condition A is satisfied in a particularslot in which a PDCCH is to be received.

If the above described condition A for a PDCCH is determined to besatisfied at a particular time point, at step 602, both the base stationand the terminal may use all the search spaces configured for theterminal at the relevant time point. The base station may transmit aPDCCH in all the search spaces as previously configured, and theterminal may monitor a PDCCH in all the search spaces as previouslyconfigured.

If the above described condition A for the PDCCH is not satisfied at theparticular time point, at step 603, the base station and the terminalselect and use some of the pre-configured search spaces so that theabove described condition A can be satisfied at the relevant time point.The base station and the terminal may select or drop only a particularsearch space set among all the search spaces. Alternatively, the basestation and the terminal may select or drop a search space at aparticular AL in a particular search space set. Alternatively, the basestation and the terminal may select or drop some PDCCH candidates in aparticular search space set. A method for selecting or dropping a searchspace should comply with the rules pre-agreed upon between the basestation and the terminal.

In the above description, selection of only some of the search spaces(or identically selecting a particular search space) may be identicallyconstrued as dropping the remaining search spaces, except for theselected search space. In a situation in which search space set #1 andsearch space set #2 are configured, selection of search space set #1 ata particular time point may be identically regarded as dropping searchspace set #2 at the relevant time point.

Selection of a particular search space may imply that a PDCCH can betransmitted in the relevant search space from the perspective of thebase station, and may imply that blind-decoding is performed in therelevant search space from the perspective of the terminal.

Dropping of a particular search space may imply that a PDCCH is nottransmitted in the relevant search space from the perspective of thebase station, and may imply that blind-decoding is not performed in therelevant search space from the perspective of the terminal.

In the following description, a specific embodiment will propose amethod for configuring a search space. If Embodiment 1-1, Embodiment1-2, Embodiment 1-3, and Embodiment 1-4 described below do notcontradict each other, it is possible to combine Embodiments 1-1, 1-2,1-3, and 1-4 so as to practice the disclosure. A method of Embodiment1-2 may be added to and combined with a method of Embodiment 1-1, andother embodiments may be combined with each other. The followingprocedure of each embodiment for selecting a search space may be appliedto both a base station and a terminal.

Embodiment 1-1

FIG. 7 is a flowchart of a method of a base station and a terminal,according to an embodiment.

Referring to FIG. 7, as a method for selecting some of all the searchspaces at step 603 of FIG. 6, at step 701, the terminal (or the basestation) assigns a priority to a search space set according to a DCIformat configured to be monitored in each search space. At step 702,according to the priorities assigned at step 701, the terminal (or thebase station) sequentially selects a search space set until condition Ais satisfied such that a search space set having a higher priority isfirst selected.

More specifically, the method for selecting some of search spaces maycomply with the following method. If condition A for a PDCCH is notsatisfied at a particular time point (slot), among search space setsexisting at the relevant time point, the terminal (or the base station)may select a search space set, a search space type of which isconfigured as a common search space, in preference to a search spaceset, a search space type of which is configured as a UE-specific searchspace.

If there exist multiple search space sets of which a search space typeis configured as a common search space, different priorities may beassigned according to DCI formats monitored in the search space sets,and a search space set may be selected in descending order of priorityuntil condition A is satisfied. Such a priority according to a DCIformat in a common search space may comply with the priority in Table 12below (a smaller number signifies a higher priority).

TABLE 12 Priority DCI format 1 DCI format 0_0/1_0/2_2/2_3 2 DCI format2_0 3 DCI format 2_1

If all of the search space sets of which the search space type isconfigured as a common search space are selected (i.e., if condition Ais satisfied even after all the search space sets of which the searchspace type is configured as a common search space are selected), theterminal (or the base station) may select a search space set, the searchspace type of which is configured as a U-specific search space. If thereexist multiple search space sets of which the search space type isconfigured as a U-specific search space, the terminal (or the basestation) may assign different priorities according to DCI formatsmonitored in the search space sets, and may select a search space set indescending order of priority until condition A is satisfied. Such apriority according to a DCI format in a UE-specific search space maycomply with the priority in Table 13 or 14 below (a smaller numbersignifies a higher priority).

TABLE 13 Priority DCI format 1 DCI format 0_0/1_0 2 DCI format 0_1 3 DCIformat 1_1

TABLE 14 Priority DCI format 1 DCI format 0_0/1_0 2 DCI format 1_1 3 DCIformat 0_1

As shown in Table 13 and 14, the DCI format 0_0 or 1_0 corresponding toa fallback DCI format may have a higher priority than that of the DCIformat 0_1 or 1_1 corresponding to a non-fallback DCI format.

Embodiment 1-1-1

FIG. 8 is a flowchart of a method of a base station and a terminal,according to an embodiment.

Referring to FIG. 8, in a method for selecting a particular search spaceset from search space sets of which a search space type is configured asa UE-specific search space, at step 801, the terminal (or the basestation) determines whether a DCI format 0_0 or 1_0 with a CRC scrambledby a C-RNTI is configured to be monitored in a common search space.

If it is determined at step 801 that the DCI format 0_0 or 1_0 with theCRC scrambled by the C-RNTI is configured to be monitored in the commonsearch space, at step 802, the terminal (or the base station) determinesthat a search space set configured to monitor a DCI format 0_0 or 1_0with a CRC scrambled by a C-RNTI has the lowest priority among searchspace sets of which a search space type is configured as a UE-specificsearch space. A priority according to a DCI format in a UE-specificsearch space may comply with the priority in Table 15 or 16 below.

TABLE 15 Priority DCI format 1 DCI format 0_1 2 DCI format 1_1 3 DCIformat 0_0/1_0

TABLE 16 Priority DCI format 1 DCI format 1_1 2 DCI format 0_1 3 DCIformat 0_0/1_0

If it is determined at step 801 that the DCI format 0_0 or 1_0 with theCRC scrambled by the C-RNTI is not configured to be monitored in thecommon search space, at step 803, the terminal (or the base station)determines that a search space set configured to monitor a DCI format0_0 or 1_0 with a CRC scrambled by a C-RNTI has the highest priorityamong the search space sets of which a search space type is configuredas the UE-specific search space. A priority according to a DCI format ina UE-specific search space may comply with the priority in Table 13 or14.

If one or more DCI formats are configured to be monitored in one searchspace set, a priority of the relevant search space set may be determinedby a DCI format having the highest priority among the DCI formats.

Embodiment 1-2

FIG. 9 is a flowchart of a method of a base station and a terminal,according to an embodiment.

Referring to FIG. 9, as the method for selecting some of all searchspaces at step 603 of FIG. 6, at step 901, among search space setsexisting at a relevant time point, the terminal (or the base station)assigns a priority of a search space set according to a combination of asearch space type and the type of DCI format monitored in a relevantsearch space set. At step 902, according to the priorities assigned atstep 901, the terminal (or the base station) sequentially selects asearch space set until condition A is satisfied such that a search spaceset having a higher priority is first selected.

More specifically, this configuration may comply with the followingmethod. If a search space for a PDCCH does not satisfy condition A at aparticular time point (slot), among search space sets existing at arelevant time point, the terminal (or the base station) may assigndifferent priorities according to a combination of a search space typeand the type of DCI format monitored in a relevant search space, and mayselect a search space set in descending order of priority untilcondition A is satisfied.

A search space set, which is configured to monitor a DCI format 0_0,1_0, 2_2, or 2_3 and of which a search space type is a common searchspace, may have the highest priority. A search space set, which isconfigured to monitor a DCI format 2_1 and of which a search space typeis the common search space, may have the lowest priority.

If there coexists a search space set which is configured to monitor aDCI format 0_0 or 1_0 with a CRC scrambled by a C-RNTI in the commonsearch space and a search space set which is configured to monitor a DCIformat 0_0 or 1_0 with a CRC scrambled by a C-RNTI in a UE-specificsearch space, the latter may have the lowest priority.

A search space set which is configured to monitor a DCI format 0_1 or1_1 and of which a search space type is the UE-specific search space mayhave a higher priority than that of a search space set which isconfigured to monitor a DCI format 2_1 and of which a search space typeis the common search space.

A search space set which is configured to monitor a DCI format 0_1 or1_1 and of which a search space type is the UE-specific search space mayhave a higher priority than that of a search space set which isconfigured to monitor a DCI format 0_0/1_0 with a CRC scrambled by aC-RNTI and of which a search space type is the UE-specific search space.

A search space set which is configured to monitor a DCI format 0_1 or1_1 and of which a search space type is the UE-specific search space mayhave a higher priority than that of a search space set which isconfigured to monitor a DCI format 0_0 or 1_1 and of which a searchspace type is the UE-specific search space. Alternatively, a searchspace set which is configured to monitor a DCI format 0_1 or 1_1 and ofwhich a search space type is the UE-specific search space may have alower priority than that of a search space set which is configured tomonitor a DCI format 0_0 or 1_1 and of which a search space type is theUE-specific search space.

A priority according to a search space type and a DCI format may complywith the priority in Table 17 below.

TABLE 17 Priority Search space type DCI format 1 common search space DCIformat 0_0/1_0/2_2/2_3 2 common search space DCI format 2_0 3UE-specific search space DCI format 0_0/1_0 4 UE-specific search spaceDCI format 0_1/1_1 5 common search space DCI format 2_1

As shown in Table 17, among a DCI format 0_0 or 1_0 and a DCI format 0_1or 1_1 which are monitored in the UE-specific search space, the formermay have a higher priority than that of the latter.

A priority according to a search space type and a DCI format may complywith the priority in Table 18 below.

TABLE 18 Priority Search space type DCI format 1 common search space DCIformat 0_0/1_0/2_2/2_3 2 common search space DCI format 2_0 3UE-specific search space DCI format 0_1/1_1 4 UE-specific search spaceDCI format 0_0/1_0 5 common search space DCI format 2_1

As shown in Table 18, among a DCI format 0_1 or 1_1 and a DCI format 0_0or 1_0 which are monitored in the UE-specific search space, the formermay have a higher priority than that of the latter.

A priority according to a search space type and a DCI format may complywith the priority in Table 19 below.

TABLE 19 Priority Search space type DCI format 1 common search space DCIformat 0_0/1_0/2_2/2_3 2 common search space DCI format 2_0 3UE-specific search space DCI format 0_1/1_1 4 common search space DCIformat 2_1 5 UE-specific search space DCI format 0_0/1_0

If there coexists a search space set which is configured to monitor aDCI format 0_0 or 1_0 with a CRC scrambled by a C-RNTI in the commonsearch space and a search space set which is configured to monitor a DCIformat 0_0 or 1_0 with a CRC scrambled by a C-RNTI in the UE-specificsearch space, this configuration may comply with the priority in Table19.

If one search space set is configured to monitor one or more DCIformats, a priority of the relevant search space set may be determinedby a DCI format having the highest priority among the configured DCIformats.

If one or more search space sets have the same priority, a priority maybecome higher as a search space set index becomes lower (or higher).

Embodiment 1-3

If a search space for a PDCCH does not satisfy condition A at aparticular time point (slot), a base station and a terminal may assigndifferent priorities to search space sets existing at the relevant timepoint by using various methods (e.g., a search space type, a combinationof a search space type and a DCI format, and an index of a search spaceset), and may select a search space set in descending order of priorityuntil condition A is satisfied.

In the process of selecting a search space set in descending order ofpriority, if condition A is satisfied until an n-th search space set isselected and condition A is not satisfied in the case of selection of an(n+1)-th search space set, the terminal (or the base station) may selecta search space set until the n-th search space set is finally selected.A selected search space set always includes all PDCCH candidatesexisting in the relevant search space set, and does not include onlysome PDCCH candidates existing in the relevant search space set.

Embodiment 1-4

If a search space for a PDCCH does not satisfy condition A at aparticular time point (slot), a base station and a terminal may assigndifferent priorities to search space sets existing at the relevant timepoint by using various methods (e.g., a search space type, a combinationof a search space type and a DCI format, and an index of a search spaceset), and may select a search space set in descending order of priorityuntil condition A is satisfied.

If condition A is satisfied until an n-th search space set is selectedand condition A is not satisfied in the case of selection of an (n+1)-thsearch space set, the terminal (or the base station) may select onlysome PDCCH candidates in the (n+1)-th search space set so that conditionA can be satisfied. A finally-selected search space set may include someof PDCCH candidates existing in the relevant search space set.

A method for selecting some of PDCCH candidates in a particular searchspace set may comply with the following embodiments.

Embodiment 1-4-1

As a method for selecting some of PDCCH candidates in a particularsearch space set, a terminal (or a base station) may sequentially selectsearch spaces configured according to aggregation levels in a searchspace set. Different priorities may be assigned according to aggregationlevels, and a search space may be selected in descending order ofpriority.

[Method 1]

The terminal (or the base station) may preferentially select PDCCHcandidates corresponding to lower aggregation levels. PDCCH candidatesexisting at lower aggregation levels may have higher priorities.

[Method 2]

The terminal (or the base station) may preferentially select PDCCHcandidates corresponding to higher aggregation levels. PDCCH candidatesexisting at higher aggregation levels may have higher priorities.

[Method 3]

The terminal (or the base station) may determine the order ofaggregation levels to be selected on the basis of a time index, a slotindex, a subframe index, or a frame index, (in the followingdescription, it is considered to be a slot index but may correspond tovarious time indices without being limited thereto) for monitoring of arelevant search space set. For convenience of description, 1 is definedas an aggregation level index. Aggregation levels configured in a searchspace set may be mapped one-to-one to aggregation level indices. Thisrelationship is defined as a function AL(⋅). If aggregation levels areset to 1, 2, 4, and 8, an aggregation level index and an aggregationlevel may have the relationship in Table 20 below.

TABLE 20 L Aggregation level 0 1 1 2 2 4 3 8

As shown in Table 20, an aggregation level index and an aggregationlevel may have the relationship, such as AL(0)=aggregation level 1,AL(1)=aggregation level 2, AL(2)=aggregation level 4, andAL(3)=aggregation level 8. An index l_(start) of an aggregation level(first aggregation level) corresponding to the highest priority may bedetermined by Equation (2) below.l _(start)=modulo(slot index,number of all configured ALs)  (2)

In Equation (2), modulo(A,B) is a function which outputs the remainderafter dividing A by B, and the number of all configured aggregationlevels may correspond to the total number of aggregation levels, forwhich the number of PDCCH candidates is set to a value which is notzero.

An aggregation level may be sequentially selected such that anaggregation level (first aggregation level) corresponding toAL(l_(start)) determined as described above is first selected.

The terminal (or the base station) may select an aggregation level inascending order of aggregation level such that the first aggregationlevel is first selected. For example, for AL=1, 2, 4, and 8, if thefirst aggregation level is 2, an aggregation level may be selected inthe order of {2, 4, 8, 1}.

The terminal (or the base station) may select an aggregation level indescending order of aggregation level such that the first aggregationlevel is first selected. For example, for AL=1, 2, 4, and 8, if thefirst aggregation level is 2, an aggregation level may be selected inthe order of {2, 1, 8, 4}.

The terminal (or the base station) may select an aggregation level inorder of closeness of aggregation levels to the first aggregation suchthat the first aggregation level is first selected. For example, forAL=1, 2, 4, and 8, if the first aggregation level is 2, an aggregationlevel may be selected in the order of {2, 1, 4, 8} or {2, 4, 1, 8}.

An aggregation level selected in a particular slot is randomized usingMethod 3 of Embodiment 1-4-1, and thus an aggregation level, at which aPDCCH can be transmitted, can be flexibly selected.

[Method 4]

The terminal (or the base station) may determine the order ofaggregation levels to be selected on the basis of a parameter fordetermination of a search space, for example, a value of Y_(p,n) _(s,f)_(μ) in Equation (1). An index l_(start) of an aggregation level (firstaggregation level) corresponding to the highest priority may bedetermined by Equation (3) below:l _(start)=modulo(Y _(p,n) _(s,f) _(μ) ,number of all configuredALs)  (3)

The terminal (or the base station) may sequentially select anaggregation level such that an aggregation level (first aggregationlevel) corresponding to AL(l_(start)) determined as described above isfirst selected.

The terminal (or the base station) may select an aggregation level inascending order of aggregation level such that the first aggregationlevel is first selected. For example, for AL=1, 2, 4, and 8, if thefirst aggregation level is 2, an aggregation level may be selected inthe order of {2, 4, 8, 1}.

The terminal (or the base station) may select an aggregation level indescending order of aggregation level such that the first aggregationlevel is first selected. For example, for AL=1, 2, 4, and 8, if thefirst aggregation level is 2, an aggregation level may be selected inthe order of {2, 1, 8, 4}.

The terminal (or the base station) may select an aggregation level inorder of closeness of aggregation levels to the first aggregation suchthat the first aggregation level is first selected. For example, forAL=1, 2, 4, and 8, if the first aggregation level is 2, an aggregationlevel may be selected in the order of {2, 1, 4, 8} or {2, 4, 1, 8}.

The terminal (or the base station) randomizes an aggregation levelselected in a particular slot by using Method 3 of Embodiment 1-4-1, andthus an aggregation level, at which a PDCCH can be transmitted, can beflexibly selected.

Embodiment 1-4-2

As a method for selecting some of PDCCH candidates in a particularsearch space set a terminal (or a base station) may sequentially selectsearch spaces configured according to aggregation levels in a searchspace set. Different priorities may be assigned according to aggregationlevels, and a search space may be selected in descending order ofpriority.

If condition A is satisfied until a search space at an m-th aggregationlevel is selected and condition A is not satisfied in the case ofselection of a search space at an (m+1)-th aggregation level, theterminal (or the base station) may select a search space until thesearch space at the m-th aggregation level is finally selected. Theterminal (or the base station) allows a selected search space to alwaysinclude all PDCCH candidates existing in the relevant search space.

Embodiment 1-4-3

As a method for selecting some of PDCCH candidates in a particularsearch space set a terminal (or a base station) may sequentially selectsearch spaces configured according to aggregation levels in a searchspace set. Different priorities may be assigned according to aggregationlevels, and a search space may be selected in descending order ofpriority.

If condition A is satisfied until a search space at an m-th aggregationlevel is selected and condition A is not satisfied in the case ofselection of a search space at an (m+1)-th aggregation level, theterminal (or the base station) may select only some PDCCH candidates inthe search space at the (m+1)-th aggregation level so that condition Acan be satisfied. A finally-selected search space may include some ofPDCCH candidates existing in the relevant search space.

As a method for selecting some of PDCCH candidates in a particularsearch space, the terminal (or the base station) may determine the orderof PDCCH candidates to be selected on the basis of a PDCCH candidateindex. A PDCCH candidate index is an index assigned to a PDCCH candidateconstituting a search space at a particular aggregation level, and maycorrespond to a value of m_(s,n) _(CI) in Equation (1). A PDCCHcandidate index m_(s,n) _(CI) at an aggregation level L in an s-thsearch space set may be defined as 0, 1, . . . , M_(p,s) ^((L))−1, andM_(p,s) ^((L)) signifies the number of PDCCH candidates. Thisconfiguration may comply with the following methods.

[Method 5]

The terminal (or the base station) may preferentially select PDCCHcandidates having a lower PDCCH candidate index. The PDCCH candidateshaving the lower PDCCH candidate index may have a higher priority.

[Method 6]

The terminal (or the base station) may preferentially select PDCCHcandidates having a higher PDCCH candidate index. The PDCCH candidateshaving the higher PDCCH candidate index may have a higher priority.

If PDCCH candidates are selected using Method 4 or Method 5, theselected PDCCH candidates always have a relatively low or high index,and thus search spaces of all terminals are configured to have onlyPDCCH candidates always having a relatively low or high index, which mayincrease a blocking probability. Therefore, the following methods may beadditionally considered so that PDCCH candidates selected for respectiveterminals can be more randomly distributed.

[Method 7]

The terminal (or the base station) may determine an index of PDCCHcandidates to be selected on the basis of a terminal ID (e.g., aC-RNTI). As a method for selecting P PDCCH candidates from a total of MPDCCH candidates, a total of P (e.g., modulo(m_(start)+(p−1), M), p=1, .. . , P, PDCCH candidates may be sequentially selected from PDCCHcandidates having an index m_(start). Modulo calculation is used suchthat a PDCCH index does not exceed a maximum PDCCH index M−1. m_(start)may be defined by Equation (4) below:m _(start)=modulo(terminal ID,M)  (4)

The PDCCH candidates selected for the respective terminals may be morerandomly distributed using Method 7.

The terminal ID may correspond to a C-RNTI.

Alternatively, in Equation (4), in addition to a C-RNTI, the terminal IDmay correspond to one of various RNTIs scrambled to a CRC of a DCIformat to be monitored (e.g., TC-RNTI, CS-RNTI, RA-RNTI, P-RNTI,SI-RNTI, INT-RNTI, TPC-PUSCH-RNTI, TPC-PUCCH-RNTI, and TPC-SRS-RNTI).

[Method 8]

The terminal (or the base station) may determine a parameter fordetermination of a search space (e.g., an index of a PDCCH candidate tobe selected on the basis of a value of Y_(p,n) _(s,f) _(μ) in Equation(1)). A method for selecting P PDCCH candidates from a total of M PDCCHcandidates, a total of P (e.g., m_(start)+1, m_(start)+2, . . . ,modulo(m_(start)+(P−1), M), PDCCH candidates may be sequentiallyselected from PDCCH candidates having an index m_(start). m_(start) maybe determined by Equation (5) below:m _(start)=modulo(Y _(p,n) _(s,f) _(μ) ,M)  (5)

As defined in Equation (5), Y_(p,n) _(s,f) _(μ) may have a value of zerofor a common search space, and may have a value determined by an RNTIand a slot index for a UE-specific search space. PDCCH candidatesselected for respective terminal may be more randomly distributed usingMethod 8.

Embodiment 1-4-3 is described as a method for selecting some of PDCCHcandidates in a search space at a particular aggregation level, butwithout being limited thereto, may be extended and applied to a methodfor selecting some of PDCCH candidates in a particular search space,multiple search spaces, a particular search space set, or multiplesearch space set.

Various methods of Embodiment 1-4-3 may be applied only to a searchspace set, a search space type of which is configured as a UE-specificsearch space. Alternatively, the various methods of Embodiment 1-4-3 maybe applied to a search space set, a search space type of which isconfigured as a common search space or the UE-specific search space.

Embodiment 1-4-4

As a method for selecting some of PDCCH candidates in a particularsearch space set, a terminal (or a base station) may select PDCCHcandidates so that aggregation levels configured in the relevant searchspace set can be evenly selected if possible. The terminal (or the basestation) may consider an aggregation level-first/PDCCH candidateindex-second method, as a method for determining a PDCCH candidate onthe basis of a combination of an aggregation level and a PDCCH candidateindex. The aggregation level-first/PDCCH candidate index-second methodmay correspond to a method for preferentially repeating, in a searchspace at each aggregation level, a process for selecting an m-th PDCCHcandidate at an l-the aggregation level, and repeating, for (m+1)-thPDCCH candidates, the same process if the m-th PDCCH candidates are allselected in search spaces at all aggregation levels.

FIG. 10 is a flowchart of a method of a base station and a terminal,according to an embodiment.

In FIG. 10, l(=0, 1, . . . , l_(max)) signifies aggregation level index,m(=0, 1, . . . , m_(max) ^((L))) signifies PDCCH candidate index,l_(max) may be defined as the total number of aggregation levelsconfigured in a search space set, m_(max) ^((L)) may be defined as thetotal number of PDCCH candidates in an L-th search space, and L may bedefined as value of an l-th aggregation level.

At step 1001, the terminal (or the base station) initializes anaggregation level index l and a PDCCH candidate index m. In an exampleof FIG. 10, l and mare both initialized to 0.

Thereafter, the terminal (or the base station) determines initial values(i.e., indices corresponding to the highest priorities) of anaggregation level index l and a PDCCH candidate index m, and the methodsdescribed in Embodiment 1-4-1 and Embodiment 1-4-3 may be applied asmethods for the same.

At step 1002, the terminal (or the base station) selects an m-th PDCCHcandidate in a search space at an l-th aggregation level.

At step 1003, if the m-th PDCCH candidate in the search space at thel-th aggregation level is selected, the terminal (or the base station)determines whether the search spaces having been selected until nowsatisfy condition A. If condition A is not satisfied, at step 1004, theterminal (or the base station) configures a search space by using thesearch spaces having been selected until now except the PDCCH candidateselected at step 1003, and may terminate the operation.

If condition A is determined at step 1003 to be satisfied, then, theterminal (or the base station) determines a PDCCH candidate to beselected. To this end, at step 1005, the terminal (or the base station)increases an aggregation level index. The terminal (or the base station)may update I to l=l+1 so as to select a PDCCH candidate at an (l+1)-thaggregation level.

At step 1006, the terminal (or the base station) determines whether avalue of the current m is greater than a maximum value m_(max) ^((L)) atan aggregation level L corresponding to the updated aggregation levelindex l. If the value of the current m is greater than m_(max) ^((L)),at step 1005, the current aggregation level may be updated to the nextaggregation level (i.e., a value of l is updated once more).

If the value of the current m is less than or equal to m_(max) ^((L)),at step 1007, the terminal (or the base station) determines whether theupdated 1 is greater than a maximum value l_(max) of an aggregationlevel index. If the value of the updated 1 is less than or equal tol_(max), the terminal (or the base station) return to step 1002, and mayagain select the m-th PDCCH candidate at the updated l-th aggregationlevel.

If it is determined at step 1007 that the value of the updated l isgreater than l_(max), the method proceeds to step 1008, re-initializingthe value of l. Then, at step 1008, the terminal (or the base station)increases the PDCCH candidate index. The terminal (or the base station)may update m to m+1 so as to allow selection of an (m+1)-th PDCCHcandidate. If it is determined at step 1007 that the value of theupdated 1 is less than or equal to l_(max), the method returns to step1002.

After step 1008, at step 1009, the terminal (or the base station)determines whether the updated m is greater than a maximum value m_(max)^((L)) at an aggregation level L corresponding to an aggregation levelindex l. If the value of m is less than or equal to m_(max) ^((L)), themethod returns to step 1002, and an m-th PDCCH candidate is selectedagain, updated at the initialized l-th aggregation level. If the valueof m is greater than m_(max) ^((L)), the terminal (or the base station)determines that a PDCCH candidate to be selected no longer exists, andmay terminate selection of a search space.

Embodiment 1-4-5

As a method for selecting some of PDCCH candidates in a particularsearch space set, a terminal (or a base station) may comply with thefollowing methods.

[Condition 1]

Among PDCCH candidates in a search space set, it is possible to select aPDCCH candidate at a particular aggregation level including a largestnumber of CCEs which overlap a PDCCH candidate at another aggregationlevel. More specifically, if a PDCCH candidate at an aggregation level Xand a PDCCH candidate at an aggregation level Y include one or moreidentical CCEs, these CCEs may be defined as overlapping CCEs, and thenumber of times of overlapping CCEs may be defined as N_(overlapped). Aparticular CCE may overlap up to a maximum of M-times (i.e., a maximumvalue of N_(overlapped) is M), and M may correspond a total number ofaggregation levels configured in a relevant search space set. When anysearch space set includes search spaces at AL={1, 2, 4, 8}, if a largestnumber of CCEs overlap each other among all CCEs constituting therelevant search space set, a maximum value of N_(overlapped) may be 4.

[Condition 2]

If multiple PDCCH candidates satisfy condition 1, the terminal (or thebase station) may select a PDCCH candidate at the highest aggregationlevel.

[Condition 3]

If multiple PDCCH candidates satisfy condition 1 and condition 2, aPDCCH candidate having the largest sum of the numbers of overlappingCCEs may be selected.

[Condition 4]

If multiple PDCCH candidates satisfy condition 1, condition 2, andcondition 3, the terminal (or the base station) may select a PDCCHcandidate having the lowest PDCCH candidate index.

Second Embodiment

A second embodiment describes a method for reinterpreting the contentsof a resource allocation field of a DCI format.

The 5G system may include fallback DCI (DCI format 1_0) for downlinkdata scheduling, non-fallback DCI (DCI format 1_1) for downlink datascheduling, fallback DCI (DCI format 0_0) for uplink data scheduling,and non-fallback DCI (DCI format 0_1) for uplink data scheduling. In the5G system, zeros are padded to a DCI format having a relatively smallsize so that a DCI format 0_0 or 1_0 has always the same DCI size.Therefore, the DCI format having a relatively small size can have thesame size as that of a DCI format having a relatively large size. In the5G system, a CRC of the DCI format 0_0 or 1_0 may be scrambled by aC-RNTI, and may be used to schedule a unicast data channel of aterminal. The DCI format 0_0 or 1_0 may be monitored in a common searchspace or a UE-specific search space.

The 5G system supports configuration and operation of a bandwidth part,and thus the size of each DCI format may be determined under theinfluence of bandwidth part-specific configuration, the bandwidth of abandwidth part, and the like. A size of a field of frequency-axisresource allocation information in a DCI format may be determined by thebandwidth of a bandwidth part and the size of a resource block group(RBG) configured within the relevant bandwidth part.

Each field of a DCI format 0_0 or 1_0 is not affected by an RRCconfiguration for the terminal. However, a frequency resource allocationinformation field in the DCI format 0_0 or 1_0 may be affected by thesize of a particular bandwidth for monitoring of the relevant DCIformat.

A size of a frequency-axis resource allocation field in a DCI format 0_0may be defined by considering the number of RBs (N_(RB) ^(UL,BWP))corresponding to the bandwidth of an uplink bandwidth part, and maycomply with the following configuration:

-   -   Frequency domain resource allocation: ┌log₂(N_(RB)        ^(UL,BWP)(N_(RB) ^(UL,BWP)+1)/2)┐ bits

A size of a frequency-axis resource allocation field in a DCI format 0_1may be defined by considering the number of RBs (N_(RB) ^(DL,BWP))corresponding to the bandwidth of a downlink bandwidth part, and maycomply with the following configuration:

-   -   Frequency domain resource allocation: ┌log₂(N_(RB)        ^(DL,BWP)(N_(RB) ^(DL,BWP)+1)/2)┐ bits.

A method for determining a size of a frequency-axis resource allocationfield in a DCI format 0_0 or a DCI format 1_0, may comply with thefollowing method. The terminal may determine a size of a frequency-axisresource allocation field on the basis of the bandwidth size of aninitial bandwidth part. That is, N_(RB) ^(UL,BWP) and N_(RB) ^(DL,BWP)may correspond to the bandwidth size of the initial bandwidth part. Theinitial bandwidth part may correspond to a bandwidth part configured forthe terminal via a MIB at an initial access stage.

The above described method may be applied to only a case in which theDCI format 0_0 or 1_0 is monitored in a common search space.Alternatively, the above described method may be applied to a case inwhich the DCI format 0_0 or 1_0 is monitored in a common search space ora UE-specific search space.

When a size of the DCI format 0_0 or 1_0 is determined on the basis ofthe above described method, if a bandwidth size of an actually-activatedbandwidth part of the terminal is different from a bandwidth size of aninitial (or basic) bandwidth part of the terminal, frequency-axisresource allocation may be very inefficiently indicated to the terminal.When a size of the DCI format 1_0 is determined using Method 1 andinformation used to schedule a PDSCH in a currently-activated bandwidthpart is indicated to the relevant terminal in the DCI format 1_0, if abandwidth size of an initial bandwidth part corresponds to 10 MHz and asize of a currently-activated bandwidth of the terminal corresponds to100 MHz, frequency-axis resource allocation information may be indicatedonly in a bandwidth corresponding to 10 MHz, and thus frequency-axisresource allocation may be very inefficiently indicated to the terminal.

Described herein are embodiments relating to a method for reinterpretingfrequency-axis resource allocation information when data is scheduledusing a DCI format 0_0 or 1_0 in order to solve the above mentionedproblem.

If Embodiment 2-1, Embodiment 2-2, Embodiment 2-3, Embodiment 2-4,Embodiment 2-5, and Embodiment 2-6 described below do not contradicteach other, it is possible to combine Embodiments 2-1, 2-2, 2-3, 2-4,2-5, and 2-6 so as to practice the disclosure. For example, a method ofEmbodiment 2-2 may be added to and combined with a method of Embodiment2-1, and other embodiments may be combined with each other.

Embodiment 2-1

A terminal may monitor a DCI format 0_0 or 1_0 in a currently-activatedbandwidth part in a common search space or a UE-specific search space.In this example, a size of a frequency-axis resource allocation field inthe DCI format 0_0 or 1_0 may be determined on the basis of thebandwidth of an initial bandwidth part. The terminal may acquire, fromthe DCI format 0_0 or 1_0, data scheduling information in thecurrently-activated bandwidth part.

If the bandwidth of the initial bandwidth part is X RB and the bandwidthof the currently-activated bandwidth part is Y RB, the terminal maydetermine a size of a frequency-axis resource allocation informationfield in consideration of a scaling factor Z.

The scaling factor Z may be determined by the following method:Z=ceiling(Y/X); orZ=flooring(Y/X).

In consideration the scaling factor Z, a size of frequency-axisallocation information in the DCI format 0_0 or 1_0 may be determined asfollows:┌log₂(Z·N _(RB) ^(BWP)(Z·N _(RB) ^(BWP)+1)/2)┐ bits.

N_(RB) ^(BWP) may correspond to X representing a bandwidth size of aninitial uplink or downlink bandwidth part.

Embodiment 2-1 may be applied regardless of an RNTI scrambled to a CRCof the DCI format 0_0 or 1_0. Alternatively, Embodiment 2-1 may beapplied to a case in which a CRC of the DCI format 0_0 or 10 isscrambled by an RNTI.

Embodiment 2-2

A terminal may monitor a DCI format 0_0 or 1_0 with a CRC scrambled by aC-RNTI in a currently-activated bandwidth part in a common search spaceor a UE-specific search space. A size of a frequency-axis resourceallocation field in the DCI format 0_0 or 1_0 may be determined on thebasis of the bandwidth of an initial bandwidth part. The terminal mayacquire, from DCI format 0_0 or 1_0, data scheduling information in thecurrently-activated bandwidth part.

A size of frequency-axis allocation information in the DCI format 0_0 or1_0 may be determined as follows:┌log₂(N _(RB) ^(BWP)(N _(RB) ^(BWP)+1)/2)┐ bits.

N_(RB) ^(BWP) may correspond to X representing a bandwidth size of aninitial downlink or uplink bandwidth part.

If the bandwidth of an initial bandwidth part is X RB and the bandwidthof the currently-activated bandwidth part is Y RB, the terminal mayreinterpret information by using a frequency-axis resource allocationinformation field in the currently-activated bandwidth part inconsideration of a scaling factor Z. The scaling factor Z may bedetermined by the following method:Z=ceiling(Y/X); orZ=flooring(Y/X).

If frequency-axis allocation information is indicated as ┌log₂(N_(RB)^(BWP)(N_(RB) ^(BWP)+1)/2)┐ bits, the terminal may reinterpret thefrequency-axis allocation information in consideration of the size of anRBG using a scaling factor Z. The frequency-axis allocation informationmay correspond to frequency allocation type 1 as shown in Table 21below:

TABLE 21 In downlink resource allocation of type 1, the resource blockassignment information indicates to a scheduled UE a set of contiguouslyallocated localized or distributed virtual resource blocks within theactive carrier bandwidth part of size N_(BWP) ^(size) PRBs except forthe case when DCI format 1_0 is decoded in the common search space inCORESET 0 in which case the initial bandwidth part of size N_(BWP)^(size) shall be used. A downlink type 1 resource allocation fieldconsists of a resource indica- tion value (RIV) corresponding to astarting virtual resource block (RB_(start)) and a length in terms ofcontiguously allocated resource blocks L_(RBs). The resource indicationvalue is defined by; if (L_(RBs) − 1) ≤ └N_(BWP) ^(size)/2┘ then  RIV =N_(BWP) ^(size)(L_(RBs) − 1) + RB_(start) else  RIV = N_(BWP)^(size)(N_(BWP) ^(size) − L_(RBs) + 1) + (N_(BWP) ^(size) − 1 −RB_(start)) Where L_(RBs) ≥ 1 and shall not exceed N_(BWP) ^(size) −RB_(start).

Frequency allocation type 1 may indicate a start point (RB_(start)) of ascheduled data channel and the number of consecutive RBs (L_(RB))thereof. The terminal may reinterpret the start point and the number ofconsecutive RBs in consideration of the defined scaling factor. Theterminal may regard RB_(start) as RB_(start)·Z and may regard L_(RB) asL_(RB)·Z so as to reinterpret frequency allocation information.

Embodiment 2-2 may be applied regardless of an RNTI scrambled to a CRCof the DCI format 0_0 or 1_0. Alternatively, Embodiment 2-2 may beapplied to a case in which a CRC of the DCI format 0_0 or 1_0 isscrambled by a C-RNTI.

A base station may transmit frequency-axis allocation information byusing DCI in consideration of the size of a currently-activatedbandwidth part, and the terminal may reinterpret the acquired DCI inconsideration of the size of a currently-activated bandwidth part.

A method for reinterpreting a field in DCI which complies withEmbodiment 2-2 is not limited to a DCI format 0_0 or 1_0, but can beextended and applied to a DCI format 0_1 or 1_1. A currently-activatedbandwidth part is assumed to be a first bandwidth part and a bandwidthindicated in DCI (i.e., a bandwidth part in which a PDSCH or a PUSCH isactually scheduled) is assumed to be a second bandwidth part. If abandwidth of a first bandwidth part is X RB and a bandwidth of a secondbandwidth part is Y RB, in order to reinterpret frequency-axis resourceallocation information in a DCI format 0_1 or 1_1, a scaling factor Zmay be defined as follows:Z=ceiling(Y/X) or Z=flooring(Y/X).

A size of a frequency-axis resource allocation field in the DCI format0_1 or 1_1 may be determined as the bandwidth of a first bandwidth part.The terminal may reinterpret the contents of a frequency-axis resourceallocation field in DCI, received in the first bandwidth part, inconsideration of the scaling factor Z.

[Frequency Allocation Type 0 (i.e., Bitmap Scheme)]

A frequency-axis resource allocation field in DCI, acquired in a firstbandwidth part, may indicate an allocated resource in a bitmap for an RBin which data is scheduled. A bitmap may be indicated in the unit ofRBG. If the size of an RBG in the first bandwidth part is set to W, wheninformation of the frequency-axis resource allocation field in therelevant DCI is interpreted, the terminal may regard the size of RBG asW·Z so as to reinterpret the information of the frequency-axis resourceallocation field in the relevant DCI as frequency-axis allocationinformation for a second bandwidth part.

[Frequency Allocation Type 1]

A frequency-axis resource allocation field in DCI, acquired in a firstbandwidth part, may indicate a start point (RB_(start)) of a channel andthe number of consecutive RBs (L_(RB)) thereof. The terminal mayreinterpret the start point and the number of consecutive RBs inconsideration of the defined scaling factor Z. The terminal may regardRB_(start) as RB_(start)·Z and may regard L_(RB) as L_(RB)·Z, and mayreinterpret RB_(start)·Z and L_(RB)·Z as frequency-axis allocationinformation for a second bandwidth part.

Embodiment 2-3

A terminal may monitor a DCI format 0_0 or 1_0 in a currently-activatedbandwidth part in a common search space or a UE-specific search space. Asize of a time-axis resource allocation field in the DCI format 0_0 or1_0 may be determined on the basis of a predefined time-axis resourceallocation table (which is named “first time-axis resource allocationtable”). The time-axis resource allocation table may be configured by acombination of pieces of information, including a mapping type of a datachannel, a start symbol of a data channel, the length of a data channel,a start slot of a data channel, and the like. The terminal may acquire,from the DCI format 0_0 or 1_0, data scheduling information in thecurrently-activated bandwidth part.

The following methods may be considered as a method for reinterpretinginformation by using a time-axis resource allocation field in a DCIformat 0_0 or 1_0 as a time-axis resource allocation information fieldin a currently-activated bandwidth part.

[Method 9]

Time-axis resource allocation information may be acquired on the basisof a predefined first time-axis resource allocation table. A firsttime-axis resource allocation table may have four entries, and one ofthe values in the table may be indicated using two bits. A base stationmay indicate, to a terminal, only one of the values in the firsttime-axis resource allocation table, and when bits of a relevant DCIfield are interpreted, the terminal may interpret the bits of therelevant DCI field on the basis of the first time-axis resourceallocation table, and may apply a result of the interpretation.

[Method 10]

Time-axis resource allocation information may be acquired on the basisof a time-axis resource allocation table configured for a bandwidth partcurrently being activated. Consideration is given to a case in which afirst time-axis resource allocation table may have four entries and thusthe size of a time-axis resource allocation field in DCI may beindicated using two bits. The time-axis resource allocation table in thebandwidth part currently being activated may include 16 entries. In thisconfiguration, one of four entries among the 16 entries may be indicatedto a terminal by using two bits of DCI. The terminal may map thecontents of the DCI, indicated by the two bits, to the time-axisresource allocation table configured for the bandwidth part currentlybeing activated so as to reinterpret the contents of the DCI.

Embodiment 2-4

FIG. 11 is a flowchart of a terminal procedure, according to anembodiment.

Referring to FIG. 11, at step 1101, a terminal monitors a PDCCH in abandwidth part currently being activated. At step 1102, the terminalacquires a DCI format 0_0 or 1_0, a CRC of which is scrambled by aC-RNTI. At step 1103, the terminal determines whether the type of searchspace, in which the DCI has been acquired at step 1102, is a commonsearch space.

If the type of the search space is determined at step 1103 to be acommon search space, at step 1104, the terminal may apply a firstinterpretation method to a resource allocation field (a frequency-axisresource allocation field, a time-axis resource allocation field, or afrequency/time-axis resource allocation field) of the acquired DCI. Thefirst interpretation method may correspond to Embodiment 2-2 in relationto frequency-axis resource allocation information, and may correspond toEmbodiment 2-3 in relation to time-axis resource allocation information.

If the type of the search space is determined at step 1103 not to be acommon search space (i.e., if the type of the search space correspondsto a UE-specific search space), at step 1105, the terminal may apply asecond interpretation method to the resource allocation field (afrequency-axis resource allocation field, a time-axis resourceallocation field, or a frequency/time-axis resource allocation field) ofthe acquired DCI. The second interpretation method may correspond to amethod for determining frequency-axis resource allocation information onthe basis of the bandwidth size of the bandwidth part currently beingactivated, and may correspond to a method for determining time-axisresource allocation information on the basis of a time-axis resourceallocation table configured for the bandwidth part currently beingactivated.

Embodiment 2-5

FIG. 12 is a flowchart of a terminal procedure, according to anembodiment.

Referring to FIG. 12, at step 1201, a terminal monitors a PDCCH in abandwidth part currently being activated. At step 1202, the terminalacquires DCI, a CRC of which is scrambled by a C-RNTI. At step 1203, theterminal determines whether a format of the DCI acquired at step 1202corresponds to 0_0 or 1_0.

If the format of the DCI is determined at step 1203 to correspond to 0_0or 1_0, at step 1204, the terminal applies a first interpretation methodto a resource allocation field (a frequency-axis resource allocationfield, a time-axis resource allocation field, or a frequency/time-axisresource allocation field) of the acquired DCI. The first interpretationmethod may correspond to Embodiment 2-2 in relation to frequency-axisresource allocation information, and may correspond to Embodiment 2-3 inrelation to time-axis resource allocation information.

If the format of the DCI is determined at step 1203 not to correspond to0_0 or 1_0, at step 1205, the terminal applies a second interpretationmethod to the resource allocation field (a frequency-axis resourceallocation field, a time-axis resource allocation field, or afrequency/time-axis resource allocation field) of the acquired DCI. Thesecond interpretation method may correspond to a method for determiningfrequency-axis resource allocation information on the basis of thebandwidth size of the bandwidth part currently being activated, and maycorrespond to a method for determining time-axis resource allocationinformation on the basis of a time-axis resource allocation tableconfigured for the bandwidth part currently being activated.

Embodiment 2-6

FIG. 13 is a flowchart of a terminal procedure, according to anembodiment.

Referring to FIG. 13, at step 1301, a terminal monitors a PDCCH in abandwidth part currently being activated. At step 1302, the terminalacquires a DCI format 0_0 or 1_0. At step 1303, the terminal determineswhether a CRC of the DCI acquired at step 1302 is scrambled by a C-RNTI.

If the CRC of the acquired DCI format 0_0 or 1_0 is determined at step1303 to be scrambled by the C-RNTI, at step 1304, the terminal applies afirst interpretation method to a resource allocation field (afrequency-axis resource allocation field, a time-axis resourceallocation field, or a frequency/time-axis resource allocation field) ofthe acquired DCI. The first interpretation method may correspond toEmbodiment 2-2 in relation to frequency-axis resource allocationinformation, and may correspond to Embodiment 2-3 in relation totime-axis resource allocation information.

If the CRC of the acquired DCI format 0_0 or 1_0 is determined at step1303 not to be scrambled by the C-RNTI (i.e., if the CRC thereof isscrambled by an RNTI other than the C-RNTI), at step 1305, the terminalapplies a second interpretation method to the resource allocation field(a frequency-axis resource allocation field, a time-axis resourceallocation field, or a frequency/time-axis resource allocation field) ofthe acquired DCI. The second interpretation method may correspond to amethod for determining frequency-axis resource allocation information onthe basis of the bandwidth size of the bandwidth part currently beingactivated, and may correspond to a method for determining time-axisresource allocation information on the basis of a time-axis resourceallocation table configured for the bandwidth part currently beingactivated.

Embodiment 2-7

Embodiment 2-7 describes a method for determining a DCI size of a DCIformat 2_0 or 2_1.

First, a DCI format 2_0 and a DCI format 2_1 of the 5G system will bebriefly described.

A DCI format 2_0 may be transmitted to indicate a slot format to aterminal group. One slot may be configured by a combination of downlinksymbols, uplink symbols, and flexible symbols, and a particular combinedform may be defined as a slot format. Each of 14 symbols in a slot maybe one of a downlink symbol, an uplink symbol, and a flexible symbol. ADCI format 2_0 may be transmitted to indicate which slot format aparticular slot has. A CRC of the DCI format 2_0 may be scrambled by anSFI-RNTI. The DCI format 2_0 may include, for example, the followinginformation:

-   -   DCI format identifier—[1] bit;    -   Slot format indicator 1, slot format indicator 2, . . . , and        slot format indicator N.

A payload size of the DCI format 2_0 may be configured by higher layersignaling (e.g., RRC signaling), and may be configured up to a maximumof 128 bits.

A DCI format 2_1 may notify a terminal group of a set of symbols and RBsin a particular time and frequency resource domain, and a terminal mayassume that no transmission intended for the terminal itself exists inthe resource domain indicated by the DCI format 2_1. A CRC of the DCIformat 2_1 may be scrambled by an INT-RNTI. The DCI format 2_1 mayinclude the following information:

-   -   DCI format identifier—[1] bit;    -   Pre-emption indicator 1, pre-emption indicator 2, . . . , and        pre-emption indicator N.

A payload size of the DCI format 2_1 may be configured by higher layersignaling (e.g., RRC signaling), and may be configured up to a maximumof 126 bits.

Both the DCI format 2_0 and the DCI format 2_1 may be monitored in acommon search space.

The terminal may perform blind-decoding for DCI formats having differentsizes monitored in the same search space or PDCCH candidate, in whichblind-decoding is performed for each DCI format. In contrast, theterminal may perform only one blind-decoding for multiple DCI formatsall having the same size monitored in the same search space, and maydistinguish between different DCI formats by using an RNTI scrambled toa CRC or a DCI format identifier existing in DCI. Accordingly, differentDCI formats to be identical are adjusted to all have the same size,making it possible to effectively reduce the number of times ofexecution of blind-decoding by the terminal.

For the above described purpose, the 5G system ensures that a DCI format0_0 always has the same size as that of a DCI format 1_0 so as to reducethe number of times of execution of blind-decoding by a terminal. If apayload size of the DCI format 0_0 is smaller than that of the DCIformat 1_0, zeros may be padded to the DCI format 0_0 so that the DCIformat 1_0 can have the same size as that of the DCI format 0_0.

In Embodiment 2-7, in a method for determining sizes of a DCI format 2_0or 2_1, if the DCI format 2_0 or 2_1 has a smaller size than that of aDCI format 0_0/1_0, zeros are padded to the DCI format 2_0 or 2_1 so asto enable the DCI format 2_0 or 2_1 to have the same size as that of theDCI format 0_0/1_0.

The DCI format 2_0 or 2_1 is allowed to have the same size as that ofthe DCI format 0_0/1_0, and thus, if the DCI format 2_0 or 2_1 and theDCI format 0_0/1_0 are monitored in the same search space or PDCCHcandidate, the number of times of execution of blind-decoding can bereduced.

If the DCI format 2_0 or 2_1 has a larger size than that of the DCIformat 0_0/1_0, adjustment which allows the DCI format 2_0 or 2_1 tohave the same size as that of the DCI format 0_0/1_0 may not beperformed. The size configured for the DCI format 2_0 or 2_1 by a basestation may be maintained as it is.

Sizes of the DCI format 2_0 and the DCI format 2_1 may be set to amaximum of 128 bits and a maximum of 126 bits, respectively. The purposeof supporting a very large number of bits as described above may be toindicate multiple cells or component carriers in a particular cell.Accordingly, when the DCI format 2_0 or 2_1 has a larger size than thatof the DCI format 0_0/1_0, if a part of a payload of the DCI format 2_0or 2_1 is truncated to allow the DCI format 2_0 or 2_1 to have the samesize as that of the DCI format 0_0/1_0, it is possible to limit controlinformation which can be indicated using the DCI format 2_0 or 2_1.

When the DCI format 2_0 or 2_1 has a larger size than that of the DCIformat 0_0/1_0, it is not desirable to pad zeros to the DCI format0_0/1_0 in order to allow relevant pieces of DCI to have the same sizes.Since the DCI format 0_0/1_0 can be used not only to schedule a unicastPDSCH but also to schedule a broadcast PDSCH, the DCI format 0_0/1_0should be defined to have the size of DCI which is common for allterminals, and thus it is not desirable for the DCI to have a variablesize.

Procedures of a base station and a terminal which comply with Embodiment2-7 will be described below.

If a DCI format 2_0 or 2_1 to be transmitted has a smaller size thanthat of a DCI format 0_0/1_0, the base station may pad zeros to the DCIformat 2_0 or 2_1 so as to cause the DCI format 2_0 or 2_1 to have thesame size as that of the DCI format 0_0/1_0, and may then transmit DCIaccording to the DCI format 2_0 or 2_1. If the DCI format 2_0 or 2_1 tobe transmitted has a larger size than that of the DCI format 0_0/1_0,the base station does not change the size of the DCI format 2_0 or 2_1,and may then transmit, as it is, DCI having a size according to thepre-configuration.

If the DCI format 2_0 or 2_1 to be transmitted by the base station has asmaller size than that of the DCI format 0_0/1_0, the terminal mayperform blind-decoding on the assumption that zeros are padded to theDCI format 2_0 or 2_1 so as to cause the DCI format 2_0 or 2_1 to havethe same size as that of the DCI format 0_0/1_0. If the DCI format 2_0or 2_1 to be transmitted by the base station has a larger size than thatof the DCI format 0_0/1_0, the terminal may perform blind-decoding onthe assumption that the DCI format 2_0 or 2_1 has a size according tothe pre-configuration.

Embodiment 2-8

A terminal may monitor a DCI format 0_0 or 1_0 with a CRC scrambled by aC-RNTI in a currently-activated bandwidth part in a common search spaceor a UE-specific search space. A size of a frequency-axis resourceallocation field in the DCI format 0_0 or 1_0 may be determined on thebasis of the bandwidth of an initial bandwidth part. The terminal mayacquire, from the DCI format 0_0 or 1_0, data scheduling information inthe currently-activated bandwidth part.

If a bandwidth of the initial bandwidth part is X RB and a bandwidth ofthe currently-activated bandwidth part is Y RB, the terminal mayreinterpret information by using a frequency-axis resource allocationinformation field in the currently-activated bandwidth part inconsideration of a scaling factor Z. The scaling factor Z may bedetermined by the following methods.

If frequency-axis allocation information is indicated to the terminal byusing frequency allocation type 1 described in Table 21, the terminalmay reinterpret the frequency-axis allocation information inconsideration of the size of an RBG using a scaling factor Z. Frequencyallocation type 1 may indicate a start point (RB_(start)) of a scheduleddata channel and the number of consecutive RBs (L_(RB)) thereof. Theterminal may reinterpret the start point and the number of consecutiveRBs in consideration of the defined scaling factor. The terminal mayregard RB_(start) as RB_(start)·Z and may regard L_(RB) as L_(RB)·Z soas to reinterpret frequency allocation information.

The above described method may be identically considered as a method forinterpreting frequency-axis allocation information for thecurrently-activated bandwidth part corresponding to Y RB by using atotal of X RBGs, each of which includes Z RBs. In the followingdescription, a specific method for configuring an RBG and a specificmethod for determining a scaling factor Z will be proposed.

[Method 11]

As a method for grouping Y RBs into X RBGs, each of the X RBGs mayinclude Z RBs. Z may have the value described below:Z=ceiling(Y/X) or Z=flooring(Y/X).

Among Y RBs, only Z*X RBs from may be utilized for frequency-axisresource allocation, and a (Y−X*Z) number of RBs are not considered forresource allocation. As a specific example, if Y=25 RBs and X=12 RBs, Zmay be 2 RBs and RBs of Y may be regarded as including a total of 12RBGs, the size of each of which is 2 RBs. Accordingly, in the case ofreinterpretation of scheduling information of a bandwidth part having abandwidth of Y RB representing a bandwidth of the currently-activatedbandwidth part by using a frequency-axis field, the size of which hasbeen determined on the basis of the bandwidth X RB of the initialbandwidth part, a part corresponding to (Y−X*Z)=24 RBs among Y=25 RBsmay be reinterpreted and scheduled.

The terminal may reinterpret frequency-axis allocation information inconsideration of the size of an RBG using the scaling factor Z. Whenfrequency-axis allocation information is indicated to the terminal byusing frequency allocation type 1 described in Table 21, frequencyallocation type 1 may indicate a start point (RB_(start)) of a scheduleddata channel and the number of consecutive RBs (L_(RB)) thereof. Theterminal may reinterpret the start point and the number of consecutiveRBs in consideration of the defined scaling factor. The terminal mayregard RB_(start) as RB_(start)·Z and may regard L_(RB) as L_(RB)·Z soas to reinterpret frequency allocation information.

[Method 12]

As a method for grouping Y RBs into X RBGs, among the X RBGs, some RBGsmay include RBs of a first RBG size Z1 and some other RBGs may includeRBs of a second RBG size Z2. Z1 and Z2 may be defined by the equationsbelow, respectively:Z1=ceiling(Y/X) or flooring(Y/X);Z2=Y−(X−1)*Z1.

An (X−1) number of RBGs may be regarded as an RBGs, each of whichincludes Z1 RBs, and one last RBG may be regarded as an RBG including Z2RBs. One last RBG may include the remaining RBs except for an (X−1)number of RBGs, each of which includes Z1 RBs, among all Y RBs. By usingthe above described method, all of Y RBs may be utilized forfrequency-axis resource allocation. Accordingly, when frequency-axisresource allocation is reinterpreted, if scheduling informationincluding RBGs having different sizes is acquired, with respect to therelevant information, instead of simply considering scaling, schedulinginformation may be reinterpreted in consideration of sizes of RBGshaving different sizes. If a frequency-axis field calculated inconsideration of X RBs indicates scheduling including an X-th RB, theterminal may regard the X-th RB as having a size of (X−Z*Y) and mayreinterpret the X-th RB as frequency-axis allocation information for YRBs.

As a specific example, if Y=25 RBs and X=12 RBs, Z1 may be 2 RBs, RBs ofY may include a total of 11 RBGs, the size of each of which 2 RBs, andthe last RBG may be regarded as having a size of 3 RBs. Accordingly,when scheduling information of a bandwidth part having a bandwidth of Y(=25) RBs is reinterpreted by using a frequency-axis field, the size ofwhich has been determined on the basis of a bandwidth of X (=12) RBs,all the 25 RBs may be utilized for scheduling. A last RBG may beregarded as having a size of Z2 (=3) not Z RBs so as to interpretscheduling information, wherein the last RBG corresponds a case in whichinformation is reinterpreted as being scheduled in a state of includingthe last RBG (e.g., an RBG having a size of 3 RBs).

The terminal may reinterpret frequency-axis allocation information inconsideration of the size of an RBG using the scaling factors Z1 and Z2.When frequency-axis allocation information is indicated using frequencyallocation type 1 described in Table 21, frequency allocation type 1 mayindicate a start point (RB_(start)) of a scheduled data channel and thenumber of consecutive RBs (L_(RB)) thereof. The terminal may reinterpretthe start point and the number of consecutive RBs in consideration ofthe defined scaling factor. If an RB index represented by RB_(start)corresponds to 0≤n<X, a frequency-axis resource allocation start pointmay be interpreted as RB_(start)·Z1, and if an RB index represented byRB_(start) corresponds to n=X, a frequency-axis resource allocationstart point may be interpreted as RB_(start)·Z2. Also, if the number ofRBs allocated to the entire frequency-axis is L_(RB), the total numberof RBs, an RB index of each of which corresponds to 0≤n<X among L_(RB)RBs is L_(RB,1), and the total number of RBs, an RB index of each ofwhich corresponds to n=X is L_(RB,2), a frequency-axis resourceallocation length may be regarded as L_(RB,1)*Z1+L_(RB,2)*Z2 andL_(RB,1)*Z1+L_(RB,2)*Z2 may be reinterpreted as frequency allocationinformation for the currently-activated bandwidth part.

[Method 13]

As a method for grouping Y RBs into X RBGs, among the X RBGs, each of N1RBGs may include RBs of a first RBG size Z1 and each of N2 RBGs mayinclude RBs of a second RBG size Z2. In this example, N1, N2, Z1, Z2 maybe defined by equations below, respectively: The number of RBGs having afirst RBG size: N1=mod(Y,X);

The number of RBGs having a second RBG size: N2=X−N1;

First RBG size: Z1=ceiling(Y/X);

Second RBG size: Z2=flooring(Y/X);X=N1+N2.

If an RB index is defined as n_(RB)=0, 1, 2, 3, . . . , Y−1, and an RBGindex is defined as n_(RBG)=0, 1, 2, . . . , X−1, a relationship betweenRBGs having the first RBG size and RBs constituting a relevant RBG, anda relationship between RBGs having the second RBG size and RBsconstituting a relevant RBG may be defined as follows:

Index of an RBG having a first RBG size: 0≤n_(RBG)<N1;

Indices of RBs having the first RBG size: n_(RBG)*Z1+n_(RB),0≤n_(RB)<Z1;

Index of an RBG having a second RBG size: N1≤n_(RBG)≤N1+N2;

Indices of RBs having the second RBG size: N1*Z1+(n_(RBG)−N1)*Z2+n_(RB),0≤n_(RB)<Z2;

As a specific example, if Y (=30) RBs and X (=12) RBs, Z1 (=3) RBs, Z2(=2) RBs, N1=6, and N2=6. By using the above described method, if Y(=30)RBs are grouped into X (=12) RBGs (e.g., RBG0, RBG1, RBG2, . . . ,RBG11) among Y (=30) RBs, RB indices of which correspond to n=0, 1, 2, .. . , 17, may be grouped by Z1=3 so as to configure a total of 6 RBGs(RBG0, RBG1, RBG2, . . . , RBG5), and RBs, RB indices of whichcorrespond to n=18, 19, 20, . . . , 29, may be grouped by Z2=2 so as toconfigure a total of 6 RBGs (RBG6, RBG7, RBG8, . . . , RBG11).

The terminal may reinterpret and acquire a frequency-axis resourceallocation field in a DCI format 0_0 or 1_0, the size of which has beencalculated with reference to a bandwidth X RB of an initial bandwidthpart, as data scheduling information of a bandwidth Y RB of acurrently-activated bandwidth part. By using the above described method,Y RBs may be grouped into X RBGs, the contents of an n (0≤n<X−1)-th RBin the contents of a frequency-axis resource allocation field indicatedwith reference to the initial bandwidth part (e.g., X RB), may be mappedone-to-one to the contents of an n (0≤n<X−1)-th RBG in an X RBG, whichis based on the currently-activated bandwidth part, so as to be applied.The terminal may apply a scaling factor Z1 to RBs, RB indices of whichcorrespond to 0≤n<N1, in the contents of the frequency-axis resourceallocation field indicated with reference to the initial bandwidth part,and thus may reinterpret the relevant contents, and may apply a scalingfactor Z2 to RBs, RB indices of which correspond to N1≤n<N1+N2 so as toreinterpret the relevant contents.

When frequency-axis allocation information is indicated using frequencyallocation type 1 described in Table 21, frequency allocation type 1 mayindicate a start point (RB_(start)) of a scheduled data channel and thenumber of consecutive RBs (L_(RB)) thereof. The terminal may reinterpretthe start point and the number of consecutive RBs in consideration ofthe defined scaling factor. If an RB index represented by RB_(start)corresponds to 0<n<N1, a frequency-axis resource allocation start pointmay be interpreted as RB_(start)·Z1, and if the RB index represented byRB_(start) corresponds to N1<n<N1+N2, the frequency-axis resourceallocation start point may be interpreted as RB_(start)·Z2. Also, if thenumber of RBs allocated to the entire frequency axis is L_(RB), thetotal number of RBs, RB indices of which correspond to 0≤n<N1 amongL_(RB) RBs is L_(RB,1), and the total number of RBs, RB indices of whichcorrespond to N1<n<N1+N2 is L_(RB,2), a frequency-axis resourceallocation length may be regarded as L_(RB,1)*Z1+L_(RB,2)*Z2 so as toreinterpret frequency allocation information.

[Method 14]

As a method for grouping Y RBs into X RBGs, among the X RBGs, each of N1RBGs may include RBs of a first RBG size Z1 and each of N2 RBGs mayinclude RBs of a second RBG size Z2. In this example, N, N2, Z1, Z2 maybe defined by equations below, respectively:

The number of RBGs having a first RBG size: N1=X−N2;

The number of RBGs having a second RBG size: N2=mod(Y,X);

First RBG size: Z1=flooring(Y/X);

Second RBG size: Z2=ceiling(Y/X);X=N1+N2.

If an RB index is defined as n_(RB)=0, 1, 2, 3, . . . , Y−1, and an RBGindex is defined as n_(RBG)=0, 1, 2, . . . , X−1, a relationship betweenRBGs having the first RBG size and RBs constituting a relevant RBG, anda relationship between RBGs having the second RBG size and RBsconstituting a relevant RBG may be defined as follows:

Index of an RBG having a first RBG size: 0≤n_(RBG)<N1;

Indices of RBs having the first RBG size: n_(RBG)*Z1+n_(RB),0≤n_(RB)<Z1;

Index of an RBG having a second RBG size: N1≤n_(RBG)≤N1+N2;

Indices of RBs having the second RBG size: N1*Z1+(n_(RBG)−N1)*Z2+n_(RB),0≤n_(RB)<Z2.

As a specific example, if Y (=30) RBs and X (=12) RBs, Z1 (=2) RBs, Z2(=3) RBs, N1=6, and N2=6. By using the above described method, if Y(=30)RBs are grouped into X (=12) RBGs (e.g., RBG0, RBG1, RBG2, . . . ,RBG11) among Y (=30) RBs, RB indices of which correspond to n=, 1, 2, .. . , 17, may be grouped by Z1=2 so as to configure a total of 6 RBGs(RBG0, RBG1, RBG2, . . . , RBG5), and RBs, RB indices of whichcorrespond to n=18, 19, 20, . . . , 29, may be grouped by Z2=3 so as toconfigure a total of 6 RBGs (RBG6, RBG7, RBG8, . . . , RBG11).

The terminal may reinterpret and acquire a frequency-axis resourceallocation field in a DCI format 0_0 or 1_0, the size of which has beencalculated with reference to a bandwidth X RB of an initial bandwidthpart, as data scheduling information of a bandwidth Y RB of acurrently-activated bandwidth part. By using the above described method,Y RBs may be grouped into X RBGs, the contents of an n (0≤n<X−1)-th RBin the contents of a frequency-axis resource allocation field indicatedwith reference to the initial bandwidth part (e.g., X RB), may be mappedone-to-one to the contents of an n (0≤n<X−1)-th RBG in an X RBG, whichis based on the currently-activated bandwidth part, so as to be applied.The terminal may apply a scaling factor Z1 to RBs, RB indices of whichcorrespond to 0≤n<N1, in the contents of the frequency-axis resourceallocation field indicated with reference to the initial bandwidth part,and thus may reinterpret the relevant contents, and may apply a scalingfactor Z2 to RBs, RB indices of which correspond to N1<n<N1+N2 so as toreinterpret the relevant contents.

When frequency-axis allocation information is indicated using frequencyallocation type 1 described in Table 21, frequency allocation type 1 mayindicate a start point (RB_(start)) of a scheduled data channel and thenumber of consecutive RBs (L_(RB)) thereof. The terminal may reinterpretthe start point and the number of consecutive RBs in consideration ofthe defined scaling factor. If an RB index represented by RB_(start)corresponds to 0<n<N1, a frequency-axis resource allocation start pointmay be interpreted as RB_(start)·Z1, and if the RB index represented byRB_(start) corresponds to N1<n<N1+N2, the frequency-axis resourceallocation start point may be interpreted as RB_(start)·Z2. Also, if thenumber of RBs allocated to the entire frequency axis is L_(RB), thetotal number of RBs, RB indices of which correspond to 0<n<N1 amongL_(RB) RBs, is L_(RB,1), and the total number of RBs, RB indices ofwhich correspond to N1<n<N1+N2 is L_(RB,2), a frequency-axis resourceallocation length may be regarded as L_(RB,1)*Z1+L_(RB,2)*Z2 so as toreinterpret frequency allocation information.

Embodiment 2-9

A terminal may receive one or more configured bandwidth parts from abase station.

The terminal may assume the size of a DCI format 0_1 or 1_1 on the basisof configuration information of a bandwidth part currently beingactivated.

If a bandwidth part indicator transmitted using DCI indicates abandwidth part other than the bandwidth part currently being activated,this configuration may signify scheduling information of the indicatedbandwidth part.

When the terminal has received the DCI format 0_1 and a bandwidth partindicator of the received DCI indicates a bandwidth part other than thebandwidth part currently being activated, the terminal may regard allfields (however, a carrier indicator, a UL/SUL indicator, and abandwidth part indicator existing in the DCI format 0_1 are maintainedwithout any change) of the received DCI as being the same as those infallback DCI (e.g., a DCI format 0_0) so as to interpret the fields. Ifa bandwidth part indicator indicates another bandwidth part, thereceived DCI format 0_1 may be considered and interpreted as shown inTable 22 below:

TABLE 22    Carrier indicator - 0 or 3 bits  UL/SUL indicator - 1 bit Identifier for DCI formats - 1 bit  Bandwidth part indicator - 0, 1 or2 bits  Frequency domain resource assignment - [┌log₂(N_(RB) ^(UL,BWP)(N_(RB) ^(UL,BWP) + 1)/2)┐] bits  Time domain resource assignment - 4bits  Frequency hopping flag - 1 bit  Modulation and coding scheme - 5bits  New data indicator - 1 bit  Redundancy version - 2 bits  HARQprocess number - 4 bits  TPC command for scheduled PUSCH - 2 bits

When the terminal has received the DCI format 1_1 and a bandwidth partindicator of the received DCI indicates a bandwidth part other than thebandwidth part currently being activated, the terminal may regard allfields (however, a carrier indicator and a bandwidth part indicatorexisting in the DCI format 1_1 are maintained without any change) of thereceived DCI as being the same as those in fallback DCI (e.g., a DCIformat 1_0) so as to interpret the fields. If a bandwidth part indicatorindicates another bandwidth part, the received DCI format 1_1 may beconsidered and interpreted as shown in Table 23 below:

TABLE 23    Carrier indicator - 0 or 3 bits  Identifier for DCIformats - 1 bit  Bandwidth part indicator - 0, 1 or 2 bits  Frequencydomain resource assignment - [┌log₂(N_(RB) ^(DL,BWP) (N_(RB) ^(DL,BWP) +1)/2)┐] bits  Time domain resource assignment - 4 bits  VRB-to-PRBmapping - 1 bit.  Modulation and coding scheme - 5 bits  New dataindicator - 1 bit  Redundancy version - 2 bits  HARQ process number - 4bits  Downlink assignment index - 2 bits  TPC command for scheduledPUCCH - 2 bits  PUCCH resource indicator - 3 bits  PDSCH-to-HARQfeedback timing indicator - 3 bits

Embodiment 2-10

A terminal may receive one or more configured bandwidth parts from abase station.

The terminal may assume the size of a DCI format 0_1 or 1_1 on the basisof configuration information of a bandwidth part currently beingactivated.

If a bandwidth part indicator transmitted using DCI indicates abandwidth part other than the bandwidth part currently being activated,this configuration may signify scheduling information of the indicatedbandwidth part.

If a currently-activated bandwidth part is A, a bandwidth part indicatedby a bandwidth part indicator is B, a bandwidth of bandwidth part A is XRB, a bandwidth of bandwidth part B is Y RB, and bandwidth part A has asmaller bandwidth than that of bandwidth part B, the reinterpretationmethod described below may be applied to DCI field which indicatesfrequency-axis resource allocation information.

The terminal may group Y RB of bandwidth part B into a total of X RBGsso as to consider the X RBGs, and may further consider indices of thegrouped X RBGs together with indices of X RB of bandwidth part A. First,as a method for grouping Y RB into X RBGs, methods identical to Method11, Method 12, Method 13, and Method 14 of Embodiment 2-8 may beconsidered (in each method, an initial bandwidth part and acurrently-activated bandwidth part may be replaced by bandwidth part Aand bandwidth part B, respectively, which allows identical application).Method 13 may be considered as follows:

[Reinterpretation Method]

As a method for grouping Y RBs into X RBGs, among the X RBGs, each of N1RBGs may include RBs of a first RBG size Z1 and each of N2 RBGs mayinclude RBs of a second RBG size Z2. In this example, N1, N2, Z1, Z2 maybe defined by equations below, respectively:

The number of RBGs having a first RBG size: N1=mod(Y,X);

The number of RBGs having a second RBG size: N2=X−N1;

First RBG size: Z1=ceiling(Y/X);

Second RBG size: Z2=flooring(Y/X);X=N1+N2.

If an RB index is defined as n_(RB)=0, 1, 2, 3, . . . , Y−1, and an RBGindex is defined as n_(RBG)=0, 1, 2, . . . , X−1, a relationship betweenRBGs having the first RBG size and RBs constituting a relevant RBG, anda relationship between RBGs having the second RBG size and RBsconstituting a relevant RBG may be defined as follows:

Index of an RBG having a first RBG size: 0≤n_(RBG)<N1;

Indices of RBs having the first RBG size: n_(RBG)*Z1+n_(RB), 0≤n_(RB)<Z;

Index of an RBG having a second RBG size: N1≤n_(RBG)≤N1+N2;

Indices of RBs having the second RBG size: N1*Z1+(n_(RBG)−N1)*Z2+n_(RB),0≤n_(RB)<Z2.

As a specific example, if Y (=30) RBs and X (=12) RBs, Z1 (=3) RBs, Z2(=2) RBs, N1=6, and N2=6. By using the above described method, if Y(=30)RBs are grouped into X (=12) RBGs (e.g., RBG0, RBG1, RBG2, . . . ,RBG11) among Y (=30) RBs, RB indices of which correspond to n=0, 1, 2, .. . , 17, may be grouped by Z1=3 so as to configure a total of 6 RBGs(RBG0, RBG1, RBG2, . . . , RBG5), and RBs, RB indices of whichcorrespond to n=18, 19, 20, . . . , 29, may be grouped by Z2=2 so as toconfigure a total of 6 RBGs (RBG6, RBG7, RBG8, . . . , RBG11).

The terminal may reinterpret and acquire a frequency-axis resourceallocation field in a DCI format 0_1 or 1_1, the size of which has beencalculated with reference to a bandwidth X RB of bandwidth part A, asdata scheduling information of a bandwidth Y RB of bandwidth part B. Byusing the above described method, Y RBs may be grouped into X RBGs, thecontents of an n (0≤n<X−1)-th RB in the contents of a frequency-axisresource allocation field indicated with reference to bandwidth part A(e.g., X RB) may be mapped one-to-one to the contents of an n(0≤n<X−1)-th RBG in an X RBG, which is based on bandwidth part B, so asto be applied. The terminal may apply a scaling factor Z to RBs, RBindices of which correspond to 0≤n<N1, in the contents of thefrequency-axis resource allocation field indicated with reference tobandwidth part A, and thus may reinterpret the relevant contents, andmay apply a scaling factor Z2 to RBs, RB indices of which correspond toN1≤n<N1+N2 so as to reinterpret the relevant contents.

When frequency-axis allocation information is indicated using frequencyallocation type 0, an RBG index of bandwidth part B may be mappedone-to-one to an RB index of bandwidth part A so as to be identicallyconsidered, and frequency allocation information may be reinterpreted.

When frequency-axis allocation information is indicated using frequencyallocation type 1 described in Table 21, frequency allocation type 1 mayindicate a start point (RB_(start)) of a scheduled data channel and thenumber of consecutive RBs (L_(RB)) thereof. The terminal may reinterpretthe start point and the number of consecutive RBs in consideration ofthe defined scaling factor. If an RB index represented by RB_(start)corresponds to 0<n<N1, a frequency-axis resource allocation start pointmay be interpreted as RB_(start)·Z1, and if the RB index represented byRB_(start) corresponds to N1≤n<N1+N2, the frequency-axis resourceallocation start point may be interpreted as RB_(start)·Z2. Also, if thenumber of RBs allocated to the entire frequency axis is L_(RB), thetotal number of RBs, RB indices of which correspond to 0<n<N1 amongL_(RB) RBs is L_(RB,1), and the total number of RBs, RB indices of whichcorrespond to N1<n<N1+N2 is L_(RB,2), a frequency-axis resourceallocation length may be regarded as L_(RB,1)*Z1+L_(RB,2)*Z2 so as toreinterpret frequency allocation information.

ceiling(N) is defined as a function which returns the smallest integervalue that is greater than N. flooring(N) is defined as a function whichreturns the largest integer value that is less than N.

FIG. 14 illustrates a transmitter, a receiver, and a controller whichperform the above described embodiments in a terminal, and FIG. 15illustrates a transmitter, a receiver, and a controller which performthe above described embodiments in a base station. More specifically,FIGS. 14 and 15 illustrate a transmission/reception method between thebase station and the terminal for implementing a method for transmittingor receiving a downlink control channel and downlink control informationin a 5G communication system according to the above describedembodiments, and in order to perform the transmission/reception method,a transmitter, a receiver, and a processor of each of the base stationand the terminal need to operate according to the embodiments.

FIG. 14 is a diagram of an internal configuration of a terminal,according to an embodiment.

Referring to FIG. 14, the terminal includes a terminal processor 1401, aterminal receiver 1402, and a terminal transmitter 1403.

The terminal processor 1401 may be configured to control a series ofprocesses so that the terminal can operate according to the abovedescribed embodiments. The terminal processor 1401 may be configured todifferently control a method for selecting a search space related to adownlink control channel and a method for reinterpreting downlinkcontrol information according to embodiments. The terminal processor1401 may be referred to as a “controller”. The terminal processor 1401may include at least one processor.

The terminal receiver 1402 and the terminal transmitter 1403 may becollectively referred to as a “transceiver”. The transceiver may beconfigured to transmit or receive a signal to or from a base station.The signal may include control information and data. To this end, thetransceiver may include an RF transmitter configured to up-convert andamplify a frequency of the transmitted signal, an RF receiver configuredto low-noise-amplify the received signal and down-convert the frequency,and the like. Also, the transceiver may be configured to receive asignal through a radio channel and output the received signal to theterminal processor 1401, and may be configured to transmit a signaloutput from the terminal processor 1401 through a radio channel.

FIG. 15 is a diagram of an internal configuration of a base station,according to an embodiment.

Referring to FIG. 15, the base station includes a base station processor1501, a base station receiver 1502, and a base station transmitter 1503.

The base station processor 1501 may control a series of processes sothat the base station can operate according to the above describedembodiments. The base station processor 1501 may be configured todifferently control a method for selecting a search space related to adownlink control channel and a method for transmitting downlink controlinformation according to embodiments. The base station processor 1501may be referred to as a “controller”. The base station processor 1501may include at least one processor.

The base station receiver 1502 and the base station transmitter 1503 maybe collectively referred to as a “transceiver”. The transceiver may beconfigured to transmit or receive a signal to or from the terminal. Thesignal may include control information and data. To this end, thetransceiver may include an RF transmitter configured to up-convert andamplify a frequency of the transmitted signal, an RF receiver configuredto low-noise-amplify the received signal and down-convert the frequency,and the like. Also, the transceiver may be configured to receive asignal through a radio channel and output the received signal to thebase station processor 1501, and may be configured to transmit a signaloutput from the base station processor 1501 through a radio channel.

The term “module” used herein may represent, for example, a unitincluding one or more combinations of hardware, software and firmware.The term “module” may be interchangeably used with the terms “logic”,“logical block”, “part” and “circuit”. The “module” may be a minimumunit of an integrated part or may be a part thereof. The “module” may bea minimum unit for performing one or more functions or a part thereof.For example, the “module” may include an ASIC.

Various embodiments of the present disclosure may be implemented bysoftware including an instruction stored in a machine-readable storagemedia readable by a machine (e.g., a computer). The machine may be adevice that calls the instruction from the machine-readable storagemedia and operates depending on the called instruction and may includethe electronic device. When the instruction is executed by theprocessor, the processor may perform a function corresponding to theinstruction directly or using other components under the control of theprocessor. The instruction may include a code generated or executed by acompiler or an interpreter. The machine-readable storage media may beprovided in the form of non-transitory storage media. Here, the term“non-transitory”, as used herein, is a limitation of the medium itself(i.e., tangible, not a signal) as opposed to a limitation on datastorage persistency.

According to an embodiment, the method according to various embodimentsdisclosed in the present disclosure may be provided as a part of acomputer program product. The computer program product may be tradedbetween a seller and a buyer as a product. The computer program productmay be distributed in the form of machine-readable storage medium (e.g.,a compact disc read only memory (CD-ROM)) or may be distributed onlythrough an application store (e.g., a Play Store™). In the case ofonline distribution, at least a portion of the computer program productmay be temporarily stored or generated in a storage medium such as amemory of a manufacturer's server, an application store's server, or arelay server.

Each component (e.g., the module or the program) according to variousembodiments may include at least one of the above components, and aportion of the above sub-components may be omitted, or additional othersub-components may be further included. Alternatively or additionally,some components may be integrated in one component and may perform thesame or similar functions performed by each corresponding componentsprior to the integration. Operations performed by a module, aprogramming, or other components according to various embodiments of thepresent disclosure may be executed sequentially, in parallel,repeatedly, or in a heuristic method. Also, at least some operations maybe executed in different sequences, omitted, or other operations may beadded.

While the disclosure has been shown and described with reference tocertain embodiments thereof, it will be understood by those skilled inthe art that various changes in form and details may be made thereinwithout departing from the scope of the disclosure.

Therefore, the scope of the disclosure should not be defined as beinglimited to the embodiments, but should be defined by the appended claimsand equivalents thereof.

What is claimed is:
 1. A method performed by a user equipment (UE) in acommunication system, the method comprising: receiving a masterinformation block (MIB) on a physical broadcast channel (PBCH);receiving downlink control information (DCI) for a system informationblock (SIB) on a control resource set 0 (CORESET0) based on the MIB;identifying a bandwidth of an initial bandwidth part based on theCORESET0; receiving first DCI corresponding to a DCI format 1_0 in acommon search space; obtaining a first starting resource block of afirst allocated resource and a first length of contiguously allocatedresource blocks of the first allocated resource based on first frequencydomain resource allocation information included in the first DCI and thebandwidth of the initial bandwidth part.
 2. The method of claim 1,further comprising: receiving second DCI corresponding to the DCI format1_0 in a UE-specific search space; and obtaining a second startingresource block of a second allocated resource and a second length ofcontiguously allocated resource blocks of the second allocated resourcebased on second frequency domain resource allocation informationincluded in the second DCI, the bandwidth of the initial bandwidth part,and a scaling factor.
 3. The method of claim 2, wherein the scalingfactor is based on a bandwidth of an active bandwidth part to which thesecond DCI is applied and the bandwidth of the initial bandwidth part.4. The method of claim 3, wherein the second starting resource block ofthe second allocated resource is based on a starting resource blockassociated with the initial bandwidth part and the scaling factor, andwherein the second length of contiguously allocated resource blocks ofthe second allocated resource is based on a length of contiguouslyallocated resource blocks associated with the initial bandwidth part andthe scaling factor.
 5. A method performed by a base station in acommunication system, the method comprising: transmitting a masterinformation block (MIB) on a physical broadcast channel (PBCH);transmitting downlink control information (DCI) for a system informationblock (SIB) on a control resource set 0 (CORESET0) according to the MIB;obtaining first frequency domain resource allocation information forindicating a first allocated resource; and transmitting first DCI,including the first frequency domain resource allocation information,corresponding to a DCI format 1_0 in a common search space, wherein abandwidth of an initial bandwidth part is based on the CORESET0, andwherein a first starting resource block of the first allocated resourceand a first length of contiguously allocated resource blocks of thefirst allocated resource correspond to the first frequency domainresource allocation information and the bandwidth of the initialbandwidth part.
 6. The method of claim 5, further comprising: obtainingsecond frequency domain resource allocation information for indicating asecond allocated resource; and transmitting second DCI, including thesecond frequency domain resource allocation information, correspondingto the DCI format 1_0 in a user equipment (UE)-specific search space,wherein a second starting resource block of the second allocatedresource and a second length of contiguously allocated resource blocksof the second allocated resource correspond to the second frequencydomain resource allocation information, the bandwidth of the initialbandwidth part, and a scaling factor.
 7. The method of claim 6, whereinthe scaling factor is based on a bandwidth of an active bandwidth partto which the second DCI is applied and the bandwidth of the initialbandwidth part.
 8. The method of claim 7, wherein the second startingresource block of the second allocated resource is based on a startingresource block associated with the initial bandwidth part and thescaling factor, and wherein the second length of contiguously allocatedresource blocks of the second allocated resource is based on a length ofcontiguously allocated resource blocks associated with the initialbandwidth part and the scaling factor.
 9. A user equipment (UE) in acommunication system, the UE comprising: a transceiver; and a controllercoupled with the transceiver and configured to: receive a masterinformation block (MIB) on a physical broadcast channel (PBCH), receivedownlink control information (DCI) for a system information block (SIB)on a control resource set 0 (CORESET0) based on the MIB, identify abandwidth of an initial bandwidth part based on the CORESET0, receivefirst DCI corresponding to a DCI format 1_0 in a common search space,and obtain a first starting resource block of a first allocated resourceand a first length of contiguously allocated resource blocks of thefirst allocated resource based on first frequency domain resourceallocation information included in the first DCI and the bandwidth ofthe initial bandwidth part.
 10. The UE of claim 9, wherein thecontroller is further configured to: receive second DCI corresponding tothe DCI format 1_0 in a UE-specific search space, and obtain a secondstarting resource block of a second allocated resource and a secondlength of contiguously allocated resource blocks of the second allocatedresource based on second frequency domain resource allocationinformation included in the second DCI, the bandwidth of the initialbandwidth part, and a scaling factor.
 11. The UE of claim 10, whereinthe scaling factor is based on a bandwidth of an active bandwidth partto which the second DCI is applied and the bandwidth of the initialbandwidth part.
 12. The UE of claim 11, wherein the second startingresource block of the second allocated resource is based on a startingresource block associated with the initial bandwidth part and thescaling factor, and wherein the second length of contiguously allocatedresource blocks of the second allocated resource is based on a length ofcontiguously allocated resource blocks associated with the initialbandwidth part and the scaling factor.
 13. A base station in acommunication system, the base station comprising: a transceiver; and acontroller coupled with the transceiver and configured to: transmit amaster information block (MIB) on a physical broadcast channel (PBCH),transmit downlink control information (DCI) for a system informationblock (SIB) on a control resource set 0 (CORESET0) according to the MIB,obtain first frequency domain resource allocation information forindicating a first allocated resource, and transmit first DCI, includingthe first frequency domain resource allocation information,corresponding to a DCI format 1_0 in a common search space, wherein abandwidth of an initial bandwidth part is based on the CORESET0, andwherein a first starting resource block of the first allocated resourceand a first length of contiguously allocated resource blocks of thefirst allocated resource correspond to the first frequency domainresource allocation information and the bandwidth of the initialbandwidth part.
 14. The method of claim 13, wherein the controller isfurther configured to: obtain second frequency domain resourceallocation information for indicating a second allocated resource, andtransmit second DCI, including the second frequency domain resourceallocation information, corresponding to the DCI format 1_0 in a userequipment (UE)-specific search space, wherein a second starting resourceblock of the second allocated resource and a second length ofcontiguously allocated resource blocks of the second allocated resourcecorrespond to the second frequency domain resource allocationinformation, the bandwidth of the initial bandwidth part, and a scalingfactor.
 15. The base station of claim 14, wherein the scaling factor isbased on a bandwidth of an active bandwidth part to which the second DCIis applied and the bandwidth of the initial bandwidth part.
 16. The basestation of claim 15, wherein the second starting resource block of thesecond allocated resource is based on a starting resource blockassociated with the initial bandwidth part and the scaling factor, andwherein the second length of contiguously allocated resource blocks ofthe second allocated resource is based on a length of contiguouslyallocated resource blocks associated with the initial bandwidth part andthe scaling factor.